No exploitation reportedFix available

CVE-2026-16255

Q: Is CVE-2026-16255 actively exploited?

Active exploitation of CVE-2026-16255 has not been confirmed. Its EPSS score was 0.2% on 2026-10-29, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2026-16255?

CVE-2026-16255 has a CVSS v3 base score of 7.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N.

Incorrect Authorization in GitLab

No exploitation reported by the sources we read.

Published2026-10-22
Fixed in19.5.1 · 19.4.3 · 19.3.6
WeaknessCWE-863

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

GitLab has remediated an issue in GitLab EE affecting all versions from 12.0 before 19.3.6, 19.4 before 19.4.3, and 19.5 before 19.5.1 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.

Timeline

dates in UTC

2026-10-2201:16CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-30 09:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-16255?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-16255?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

OSV · NVD

GitLab

Branch	Affected	Fixed in	Source
19.5	≥ 19.5.0, < 19.5.1	19.5.1	OSV
19.4	≥ 19.4.0, < 19.4.3	19.4.3	NVD · OSV
19.3	≥ 12.0.0, < 19.3.6	19.3.6	NVD · OSV
19.5	= 19.5.0	no fix published	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update GitLab to 19.5.1 · 19.4.3 · 19.3.6

Advisories and patches

docs.gitlab.comRelease Notes · Vendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

CNACVSS 3.15.9read 2026-10-30
NVDCVSS 3.17.1read 2026-10-30
NVDweakness (CWE)CWE-863read 2026-10-30
FIRST EPSSEPSS score0.2 %2026-10-29
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
Published: 2026-10-22
Last Modified: 2026-10-29
NVD status: Analyzed

Frequently asked questions

What is CVE-2026-16255?

Is CVE-2026-16255 actively exploited?

Active exploitation of CVE-2026-16255 has not been confirmed. Its EPSS score was 0.2% on 2026-10-29, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-16255?

CVE-2026-16255 has a CVSS v3 base score of 7.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N.

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