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TI-2026-54240 Aliases CVE-2026-77912GHSA-6293-4rx2-2p57

Cross-site scripting in GitHub Enterprise Server

Priority LOW 34CWE-79Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
Passive
Attack complexity
High
Attack requirements
None
Impact type
Cross-site scripting
Confidentiality · integrity · availability
High · High · None
Fix status
No fix listed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-79.

Summary

A stored cross-site scripting (XSS) vulnerability was identified in GitHub Enterprise Server that allowed an authenticated attacker to inject arbitrary HTML attributes into rendered Markdown because the Markdown rendering pipeline rewrote quote characters in already-sanitized HTML without re-sanitizing the result. Crafted Markdown could abuse same-origin JavaScript gadgets to bypass Content Security Policy and gain control of the page DOM when viewed by another user. Successful exploitation could allow an attacker to read content visible to the victim, extract embedded CSRF tokens, perform state-changing actions as the victim, and exfiltrate data through same-origin writes. The payload could also propagate to repositories and organizations where the victim had write access. This vulnerability affected supported GitHub Enterprise Server releases in the 3.17, 3.18, 3.19, 3.20, 3.21, and 3.22 series and was fixed in versions 3.22.1, 3.21.6, 3.20.8, 3.19.12, 3.18.15, and 3.17.21. This vulnerability was reported via the GitHub Bug Bounty program.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00207 10th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
GitHubEnterprise Server3.17.0 and later; 3.18.0 and later; 3.19.0 and later; 3.20.0 and later; 3.21.0 and later; 3.22.0 and later—No fix listedCNA
  • Enterprise Server VendorGitHub Affected 3.17.0 and later; 3.18.0 and later; 3.19.0 and later; 3.20.0 and later; 3.21.0 and later; 3.22.0 and later Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:*3.17.0 to before 3.17.21; 3.18.0 to before 3.18.15; 3.19.0 to before 3.19.12; 3.20.0 to before 3.20.8; 3.21.0 to before 3.21.6; 3.22.0 to before 3.22.1VulnerableGitHub
  • cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:* Versions 3.17.0 to before 3.17.21; 3.18.0 to before 3.18.15; 3.19.0 to before 3.19.12; 3.20.0 to before 3.20.8; 3.21.0 to before 3.21.6; 3.22.0 to before 3.22.1 Vulnerable ·GitHub

Remediation

No fixed version listed by the sources yet.

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    GitHub Enterprise Server 3.17.*, 3.18.* and 4 more versions

    2 records Highest priority Priority MEDIUM 1 MEDIUM, 1 LOW

    Other records, highest priority first

    • TI-2026-54262 GitHub Enterprise Server notebook viewer vulnerable to Server-side request forgeryPriority MEDIUM 50
    Show all 2 records →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-77912
  2. 2026-10-03 Alias added: GHSA-6293-4rx2-2p57

References

Advisory 6

  • TI-2024-04632 An authentication bypass vulnerability was present in the GitHub Enterprise Server (GHES)… CVSS 4.0CRITICAL 10.0
  • TI-2024-00181 Unsafe Reflection in Github Enterprise Server leading to Command Injection CVSS 3.1CRITICAL 9.8
  • TI-2024-00466 Privilege Escalation by Code Injection in the Management Console in GitHub Enterprise Server CVSS 3.1HIGH 8.8
  • TI-2026-03340 Remote code execution via git push option injection in GitHub Enterprise Server CVSS 4.0HIGH 8.7
  • TI-2024-08804 Improper signature verification in GitHub Enterprise Server CVSS 4.0CRITICAL 9.5
  • TI-2026-08177 Server-side request forgery in GitHub Enterprise Server CVSS 4.0CRITICAL 9.2
See all 125 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences