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                            CERT-Renater

                Note d'Information No. 2026/VULN1063
_____________________________________________________________________

DATE                : 22/10/2026

HARDWARE PLATFORM(S): /

OPERATING SYSTEM(S): Systems running GitLab versions prior to 19.5.1,
                   19.4.3, 19.3.6, 19.2.9, 19.1.9, 19.0.10, 18.11.13.

====================================================================
https://docs.gitlab.com/releases/patches/patch-release-gitlab-19-5-1-released/
_____________________________________________________________________

GitLab Critical Patch Release: 19.5.1, 19.4.3, 19.3.6, 19.2.9,
19.1.9, 19.0.10, 18.11.13

On October 21, 2026, we released versions 19.5.1, 19.4.3, 19.3.6,
19.2.9, 19.1.9, 19.0.10, 18.11.13 for GitLab Community Edition (CE)
and Enterprise Edition (EE).

These versions contain important bug and security fixes, and we
strongly recommend that all self-managed GitLab installations be
upgraded to one of these versions immediately. GitLab.com is already
running the patched version. GitLab Dedicated tenants running
19.3.5-internal0 and 19.4.2-internal0 or later already include these
fixes and do not need to take action.

GitLab releases fixes for vulnerabilities in patch releases. There are
two types of patch releases: scheduled releases and ad-hoc critical
patches for high-severity vulnerabilities. Scheduled releases are
released twice a month on the second and fourth Wednesdays. For more
information, please visit our releases handbook and security FAQ.
You can see all of GitLab release blog posts here.

For security fixes, the issues detailing each vulnerability are made
public on our issue tracker 90 days after the release in which they
were patched.

We are committed to ensuring that all aspects of GitLab that are
exposed to customers or that host customer data are held to the
highest security standards. To maintain good security hygiene, it
is highly recommended that all customers upgrade to the latest patch
release for their supported version. You can read more best practices
in securing your GitLab instance in our blog post.


Recommended Action

We strongly recommend that all installations running a version affected
by the issues described below are upgraded to the latest version as
soon as possible.

When no specific deployment type (omnibus, source code, helm chart, etc.)
of a product is mentioned, it means all types are affected.


Security fixes

Table of security fixes

Title                     Severity
_____________________________________________________________________
Integer Overflow issue in Regular Expression Compiler impacts GitLab
CE/EE Critical

Improper Authentication issue in OmniAuth-to-LDAP auto-linking email
lookup impacts GitLab CE/EE	High

Cache Poisoning issue in OAuth/OIDC discovery endpoints impacts GitLab
CE/EE     High

Improper Access Control issue in GraphQL work item email address field
impacts GitLab CE/EE	Medium

Incomplete enforcement of instance-wide SAML/LDAP membership lock
allows unauthorized member additions in GitLab EE	Medium

Internal Credential Exposure issue in internal response headers impacts
GitLab CE/EE	Medium

Authorization Bypass Through User-Controlled Key issue in group
milestones API impacts GitLab CE/EE	Medium

Use of Less Trusted Source issue in AI Gateway feature enablement header
impacts GitLab EE	Medium

Use of Cache Containing Sensitive Information issue in merge request
title rendering impacts GitLab CE/EE	Low

Improper Access Control issue in merge request approval policy
enforcement impacts GitLab EE	Low

Improper Cleanup on Thrown Exception issue in security findings
impacts GitLab EE	Low

Improper Access Control issue in group Duo admin-lock enforcement
for Amazon Q settings impacts GitLab EE	Low


CVE-2026-110264 - Integer Overflow issue in Regular Expression
Compiler impacts GitLab CE/EE

GitLab has remediated an issue that, under certain conditions,
could have allowed an unauthenticated user to execute arbitrary
code on the GitLab server due to integer overflow when compiling a
specially crafted regular expression.

In addition to our standard patch releases, we have backported this
fix to GitLab CE/EE versions 18.11.13, 19.0.10, 19.1.9, and 19.2.9.

Impacted Versions: GitLab CE/EE: all versions from 7.0 before
18.11.13, 19.0 before 19.0.10, 19.1 before 19.1.9, 19.2 before
19.2.9, 19.3 before 19.3.6, 19.4 before 19.4.3, and 19.5 before
19.5.1
CVSS 10.0 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H)

Thanks joaxcar for reporting this vulnerability through our HackerOne
bug bounty program


Detecting CVE-2026-110264 Exploitation Attempts

GitLab security has released two threat detections to support customers
with self-managed instances, listed below. GitLab-managed infrastructure,
including GitLab.com and GitLab Dedicated, remains patched.

    Onigmo native worker crash
    Org mode render error burst


CVE-2026-15723 - Improper Authentication issue in OmniAuth-to-LDAP
auto-linking email lookup impacts GitLab CE/EE

GitLab has remediated an issue that, when OmniAuth SAML and LDAP
auto-linking were both enabled, an authenticated user could have taken
over an existing LDAP-backed account without any interaction from the
targeted user, due to improper input sanitization in the LDAP email
lookup path used during OmniAuth identity linking.

Impacted Versions: GitLab CE/EE: all versions from 10.1 before 19.3.6,
19.4 before 19.4.3, and 19.5 before 19.5.1
CVSS 8.2 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N)

Thanks stealthy for reporting this vulnerability through our HackerOne
bug bounty program


CVE-2026-112212 - Cache Poisoning issue in OAuth/OIDC discovery
endpoints impacts GitLab CE/EE

GitLab has remediated an issue that, under certain conditions, an
unauthenticated user could have poisoned a shared cache’s OAuth/OIDC
discovery document to redirect certain flows to an externally controlled
server, due to improper trust of user-supplied values when constructing
endpoint URLs in cached discovery responses.

Impacted Versions: GitLab CE/EE: all versions from 18.3 before 19.3.6,
19.4 before 19.4.3, and 19.5 before 19.5.1
CVSS 7.5 (CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:L)

This vulnerability has been discovered internally by GitLab team member
Peter Arts


CVE-2026-12664 - Improper Access Control issue in GraphQL work item
email address field impacts GitLab CE/EE

GitLab has remediated an issue that, under certain conditions, could
have allowed an authenticated user with a read_api-scoped token to
retrieve a project’s incoming email address and create work items,
bypassing the token’s restrictions, due to insufficient scope
enforcement on a GraphQL field.

Impacted Versions: GitLab CE/EE: all versions from 18.2 before 19.3.6,
19.4 before 19.4.3, and 19.5 before 19.5.1
CVSS 6.8 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N)

Thanks go7f0 for reporting this vulnerability through our HackerOne
bug bounty program


CVE-2026-16255 - Incomplete enforcement of instance-wide SAML/LDAP
membership lock allows unauthorized member additions in GitLab EE

GitLab has remediated an issue that, when the instance-wide SAML or
LDAP membership lock was enabled, an authenticated user could have
granted or accepted project and group membership outside the identity
provider’s control, due to incomplete enforcement of the membership
lock on requests created before the lock was enabled.

Impacted Versions: GitLab EE: all versions from 12.0 before 19.3.6,
19.4 before 19.4.3, and 19.5 before 19.5.1
CVSS 5.9 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N)

Thanks 3nvz for reporting this vulnerability through our HackerOne
bug bounty program


CVE-2026-105777 - Internal Credential Exposure issue in internal
response headers impacts GitLab CE/EE

GitLab has remediated an issue that, under certain conditions, an
unauthenticated user could have retrieved sensitive internal server
credentials due to improper filtering of internal response headers.

Impacted Versions: GitLab CE/EE: all versions from 17.6.5 before
19.3.6, 19.4 before 19.4.3, and 19.5 before 19.5.1
CVSS 4.3 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N)

Thanks altair00 for reporting this vulnerability through our
HackerOne bug bounty program


CVE-2026-13319 - Authorization Bypass Through User-Controlled Key
issue in group milestones API impacts GitLab CE/EE

GitLab has remediated an issue that could have allowed an
authenticated user to read milestone metadata, including titles,
descriptions, and full project paths, from arbitrary private
projects across the instance without any project membership, due
to missing authorization checks on a user-supplied project filter
parameter in the group milestones API.

Impacted Versions: GitLab CE/EE: all versions from 15.10 before
19.3.6, 19.4 before 19.4.3, and 19.5 before 19.5.1
CVSS 4.3 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N)

Thanks a0xnirudh for reporting this vulnerability through our
HackerOne bug bounty program


CVE-2026-112378 - Use of Less Trusted Source issue in AI Gateway
feature enablement header impacts GitLab EE

GitLab has remediated an issue that under certain conditions could
have allowed an authenticated user to access paid AI features without
a valid subscription due to insufficient server-side validation in
billing eligibility checks.

Impacted Versions: GitLab EE: all versions from 17.8 before 19.3.6,
19.4 before 19.4.3, and 19.5 before 19.5.1
CVSS 4.3 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N)

This vulnerability has been discovered internally by GitLab team
member Halil Coban


CVE-2026-105711 - Use of Cache Containing Sensitive Information issue
in merge request title rendering impacts GitLab CE/EE

GitLab has remediated an issue that, when a merge request in a public
project referenced a confidential issue from a private project, an
authenticated user with no project membership could have read the
confidential issue’s title, due to a viewer-independent fragment cache
key that incorrectly shared per-user-redacted rendered content across
all users.

Impacted Versions: GitLab CE/EE: all versions from 15.0 before 19.3.6,
19.4 before 19.4.3, and 19.5 before 19.5.1
CVSS 3.5 (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N)

Thanks 20kilograma for reporting this vulnerability through our HackerOne
bug bounty program


CVE-2026-14288 - Improper Access Control issue in merge request
approval policy enforcement impacts GitLab EE

GitLab has remediated an issue that under certain conditions could
have allowed an authenticated user to bypass a required merge request
approval policy on a protected branch due to improper access control
during approval rule synchronization.

Impacted Versions: GitLab EE: all versions from 17.4 before 19.3.6,
19.4 before 19.4.3, and 19.5 before 19.5.1
CVSS 3.1 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N)

Thanks 3nvz for reporting this vulnerability through our HackerOne
bug bounty program


CVE-2026-112326 - Improper Cleanup on Thrown Exception issue in
security findings impacts GitLab EE

GitLab has remediated an issue that, under certain conditions, could
have allowed an authenticated user with read-only permissions to
permanently delete existing vulnerability records due to improper
cleanup logic that failed to distinguish between pre-existing records
from newly created ones during error handling.

Impacted Versions: GitLab EE: all versions from 17.8 before 19.3.6,
19.4 before 19.4.3, and 19.5 before 19.5.1
CVSS 3.1 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N)

This vulnerability has been discovered internally by GitLab team
member Gregory Havenga


CVE-2026-103515 - Improper Access Control issue in group Duo admin-lock
enforcement for Amazon Q settings impacts GitLab EE

GitLab has remediated an issue that, when an instance administrator
locked a group’s Duo availability, an authenticated user with group Owner
permissions could have re-enabled AI-backed data egress to a third-party
service for that group and its descendant projects, due to insufficient
granularity of the admin-lock enforcement controls.

Impacted Versions: GitLab EE: all versions from 19.2 before 19.3.6,
19.4 before 19.4.3, and 19.5 before 19.5.1
CVSS 2.7 (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:N)

Thanks 3nvz for reporting this vulnerability through our HackerOne
bug bounty program


Bug fixes

19.5.1

    Backport 19.5 docs pages missing from the stable branch
    Backport 19.5 release notes to 19-5-stable-ee
    Backport of ‘Ignore CI variable in roulette experiment default specs’
    Backport of ‘Quarantine the scope picker search query spec’
    Backport GitLab Runner 19.5 release post to the latest stable branch
    Bump CNG helm chart ref to v10.5.0
    Backport of ‘Set GITLAB_BIN_DIR for Duo CLI and bump workflow image to v0.0.23’ into 19.5
    Backport of ‘Return repository_storage from internal Orbit project info’ to 19.5
    Backport of ‘Workhorse: return 429 when Gitaly rejects GetArchive with ResourceExhausted’
    Backport of ‘Allocate pipeline IID for pipeline execution policy pipelines’
    Backport of ‘Link commit list browse button to the current file path’ to 19.5
    Backport of “Load only needed snippet columns when backing up repositories”
    [19.5] Update gitlab-markup to 2.2.0 and rdoc to 8.1.0
    Backport of ‘Pin the Baseline date in .browserslistrc’ into 19.5
    Backport: Cache foundational flow catalog item per request
    Fix work item change type and child milestone with features field
    Backport of ‘Raise Rouge Fallthrough without capturing a backtrace’ to 19.5
    Backport of ‘Add What’s New entries for 202610150001_19_05’
    Backport of ‘Return 404 for Orbit archive and changed_paths when repository is missing’ to 19.5
    Backport of ‘Stop jobs without a fetch from borrowing the git object pool’ and ‘Fix downstream pipelines git alternates’
    [19.5] Add Ruby regexp repeat ID overflow patch for 3.3, 3.4 and 4.0
    [19.5] Add Ruby regexp repeat ID overflow patch for 3.3, 3.4 and 4.0

19.4.3

    Add siphon-tables image bundling Siphon CDC table definitions [19.4]
    [19.4] Add Ruby regexp repeat ID overflow patch for 3.3, 3.4 and 4.0
    Backport of “Expose opt-in tagger dates in ListRefs” to 19.4
    Backport of ‘Remove stale merge_request event from Developer flow triggers’ to 19.4
    Backport of ‘Add IP fallback errors to Gitlab::HTTP HTTP_ERRORS’ to 19.4
    Backport of ‘Resume the CVE enrichment sync across export files’ to 19.4
    Backport of ‘Fix truncated diffs for signed-out users’ into 19.4
    Backport of ‘Strip the trusted flag from client-supplied MCP tools in Workhorse’ to 19.4
    Backport of ‘Fix fast-forward merge when a tag shares the target branch name’ to 19.4
    Backport of ‘Ignore CI variable in roulette experiment default specs’
    Backport of ‘Add missing ID token claims for fork MR pipelines’ to 19.4
    Backport of “Load only needed snippet columns when backing up repositories”
    Backport of ‘Set GITLAB_BIN_DIR for Duo CLI and bump workflow image to v0.0.23’ into 19.4
    Backport of ‘Pin the Baseline date in .browserslistrc’ into 19.4
    Backport of ‘Return repository_storage from internal Orbit project info’ to 19.4
    Backport of ‘Workhorse: return 429 when Gitaly rejects GetArchive with ResourceExhausted’
    Backport of ‘Allocate pipeline IID for pipeline execution policy pipelines’
    [19.4] Update gitlab-markup to 2.2.0 and rdoc to 8.1.0
    Backport of ‘Return 404 for Orbit archive and changed_paths when repository is missing’ to 19.4
    Backport of ‘Raise Rouge Fallthrough without capturing a backtrace’ to 19.4
    Backport of ‘Remove unnecessary committer batch-load from mergeability fields’ to 19.4
    Backport of “Adjustments to Wiki experience” to 19.4
    [19.4] Add Ruby regexp repeat ID overflow patch for 3.3, 3.4 and 4.0

19.3.6

    [19.3] Add Ruby regexp repeat ID overflow patch for 3.3, 3.4 and 4.0
    Backport of “Expose opt-in tagger dates in ListRefs” to 19.3
    Backport of ‘Add IP fallback errors to Gitlab::HTTP HTTP_ERRORS’ to 19.3
    Backport of ‘Resume the CVE enrichment sync across export files’ to 19.3
    Backport of ‘Fix fast-forward merge when a tag shares the target branch name’ to 19.3
    Backport of ‘Strip the trusted flag from client-supplied MCP tools in Workhorse’ to 19.3
    Backport of ‘Add missing ID token claims for fork MR pipelines’ to 19.3
    Backport of “Load only needed snippet columns when backing up repositories”
    Backport of ‘Workhorse: return 429 when Gitaly rejects GetArchive with ResourceExhausted’
    Backport of ‘Pin the Baseline date in .browserslistrc’ into 19.3
    Backport of ‘Return repository_storage from internal Orbit project info’ to 19.3
    [19.3] Update gitlab-markup to 2.2.0 and rdoc to 8.1.0
    Backport of “Adjustments to Wiki experience” to 19.3
    Backport of ‘Raise Rouge Fallthrough without capturing a backtrace’ to 19.3
    Backport of ‘Return 404 for Orbit archive and changed_paths when repository is missing’ to 19.3
    Bump Prometheus to version 3.13.2 (19-3-stable)
    [19.3] Add Ruby regexp repeat ID overflow patch for 3.3, 3.4 and 4.0

19.2.9

    [19.2] Add Ruby regexp repeat ID overflow patch for 3.3, 3.4 and 4.0
    Backport of ‘Add missing ID token claims for fork MR pipelines’ to 19.2
    [19.2] Update gitlab-markup to 2.2.0 and rdoc to 8.1.0
    Bump Prometheus to version 3.13.2 (19-2-stable)
    [19.2] Add Ruby regexp repeat ID overflow patch for 3.3, 3.4 and 4.0

19.1.9

    Bump websocket-driver from 0.8.0 to 0.8.2 (backport to 19-1-stable-ee)
    Backport of ‘Fix backfill migration overlap on empty CI partitions’ to 19-1-stable-ee
    Backport of ‘Update GitLab Elasticsearch Indexer to 5.14.14’ to 19.1
    Backport ‘Drop system failure assertion in secrets spec’ to 19-1-stable-ee
    Bump gitlab-shell to 14.56.1 in 19.1 (gitlab-sshd CPU spin fix)
    Bump PostgreSQL to version 17.11 (19-1-stable)
    Bump Consul to version 1.22.7 (19-1-stable)
    Merge branch ‘sdg-fips-staging-upload-internal-release’ into 19.1
    Backport !9672 to 19-1-stable: selinux: add sshd_session_t and sshd_auth_t rules for RHEL 10 / OpenSSH 9.8+
    Backport !9744 to 19-1-stable: Allow sshd fast SSH key lookup under SELinux
    Treat Patroni streaming state as a running node (backport to 19-1-stable)
    [19.1] Add Ruby regexp repeat-range double-free patch for 3.3 and 3.4
    [19.1] Add Ruby regexp repeat-range double-free patch for 3.3 and 3.4

19.0.10

    Increase staging and production upload timeout from 35m to 60m
    [19.0] Add Ruby regexp repeat-range double-free patch for 3.3 and 3.4
    [19.0] Add Ruby regexp repeat-range double-free patch for 3.3 and 3.4

18.11.13

    Increase staging and production upload timeout from 35m to 60m
    Mattermost Security Updates August 13, 2026
    [18.11] Add Ruby regexp repeat-range double-free patch for 3.3 and 3.4
    [18.11] Add Ruby regexp repeat-range double-free patch for 3.3 and 3.4


Important notes on upgrading

This patch includes database migrations that may impact your upgrade
process.

Impact on your installation:

    Single-node instances: This patch will cause downtime during the
upgrade as migrations must complete before GitLab can start.
    Multi-node instances: With proper zero-downtime upgrade procedures,
this patch can be applied without downtime.


Regular migrations

The following versions include regular migrations that run during
the upgrade process:

    19.4.3
    19.3.6


Post-deploy migrations

The following versions include post-deploy migrations that can run
after the upgrade:

    19.4.3

To learn more about the impact of upgrades on your installation, see:

    Zero-downtime upgrades for multi-node deployments
    Standard upgrades for single-node installations


Updating

To update GitLab, see the Update page. To update GitLab Runner, see
the Updating the Runner page.


Receive Patch Notifications

To receive patch blog notifications delivered to your inbox, visit
our contact us page. To receive release notifications via RSS,
subscribe to our patch release RSS feed or our RSS feed for all
releases.


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