What is CVE-2026-2266?

CVE-2026-2266 is a medium-severity vulnerability in Github Enterprise Server, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-03-10.

How severe is CVE-2026-2266?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Github Enterprise Server

CVE-2026-2266

An improper neutralization of input vulnerability was identified in GitHub Enterprise Server that allowed DOM-based cross-site scripting via task list content. The task list content extraction logic did not properly re-encode browser-decoded text nodes before rendering, allowing user-supplied HTML to be injected into the page. An authenticated attacker could craft malicious task list items in issues or pull requests to execute arbitrary scripts in the context of another user's browser session. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.20 and was fixed in versions 3.18.6 and 3.19.3. This vulnerability was reported via the GitHub Bug Bounty program.

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.002 (7.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

Affected products

Github Enterprise Server — versions 3.18.0, 3.19.0
Github Enterprise_server

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

product-cna@github.com (release-notes, Release Notes)
product-cna@github.com (release-notes, Release Notes)

Frequently asked questions

What is CVE-2026-2266?: CVE-2026-2266 is a medium-severity vulnerability in Github Enterprise Server, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-03-10.
How severe is CVE-2026-2266?: Medium severity. CVSS v3 base score is 5.4 out of 10.