CVE-2021-39887
MEDIUMCVSS 5.4/10EPSS 0.84%
Last modified
CVE-2021-39887 is a medium-severity vulnerability rated 5.4/10 on the CVSS scale. A stored Cross-Site Scripting vulnerability in the GitLab Flavored Markdown in GitLab CE/EE version 8.4 and above allowed an attacker to execute arbitrary JavaScript code on the victim's behalf.. EPSS estimates a 0.84% chance of exploitation in the next 30 days.
Description
A stored Cross-Site Scripting vulnerability in the GitLab Flavored Markdown in GitLab CE/EE version 8.4 and above allowed an attacker to execute arbitrary JavaScript code on the victim's behalf.
Metrics
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Gitlab | Gitlab | >= 8.4.0, < 14.1.7 |
| Gitlab | Gitlab | >= 14.2, < 14.2.5 |
| Gitlab | Gitlab | >= 14.3, < 14.3.1 |
References
- https://hackerone.com/reports/1218174Permissions Required, Third Party Advisory
- https://hackerone.com/reports/1218174Permissions Required, Third Party Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
Frequently Asked Questions
What is CVE-2021-39887?
A stored Cross-Site Scripting vulnerability in the GitLab Flavored Markdown in GitLab CE/EE version 8.4 and above allowed an attacker to execute arbitrary JavaScript code on the victim's behalf.
How severe is CVE-2021-39887?
CVE-2021-39887 has a CVSS score of 5.4/10 (MEDIUM severity). The EPSS model estimates a 0.84% probability of exploitation in the next 30 days.
How do I fix CVE-2021-39887?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
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Are you affected by CVE-2021-39887?
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Scan your code nowSource: NVD / NIST