CVE-2026-3254

Description

GitLab has remediated an issue in GitLab CE/EE affecting all versions from 18.11 before 18.11.1 that under certain conditions could have allowed an authenticated user to load unauthorized content into another user's browser due to improper input validation in the Mermaid sandbox.

CVSS v3.1 Score

3.5

LOW

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N

EPSS — Exploit Prediction

0.0001

Probability of exploitation

0.02%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-1021 CWE-1021

Affected Products

Vendor	Product	Versions
gitlab	gitlab	All
gitlab	gitlab	All

References

Other References

https://gitlab.com/gitlab-org/gitlab/-/work_items/591587 https://hackerone.com/reports/3572752

Frequently Asked Questions

What is CVE-2026-3254? +

GitLab has remediated an issue in GitLab CE/EE affecting all versions from 18.11 before 18.11.1 that under certain conditions could have allowed an authenticated user to load unauthorized content into another user's browser due to improper input validation in the Mermaid sandbox. It has a CVSS v3.1 base score of 3.5 (LOW).

How severe is CVE-2026-3254? +

CVE-2026-3254 has a CVSS v3.1 score of 3.5 out of 10, rated LOW. This is a low-severity vulnerability with limited impact. The EPSS score is 0.0001, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-3254? +

CVE-2026-3254 affects products from gitlab, specifically: gitlab. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-3254? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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