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Vulnerability record · CVE-2026-2266 · published 10 March 2026

CVE-2026-2266: Github enterprise server cross-site scripting vulnerability

Github · Enterprise Server

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.

7.4 CVSS 4.0 High EPSS 0.18% · top 93.7% CWE-79 · Cross-site scripting
7.4CVSS 4.0 base score
0.18%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

Description

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.

CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://docs.github.com/en/[email protected]/admin/release-notes#3.18.6 Release Notes
https://docs.github.com/en/[email protected]/admin/release-notes#3.19.3 Release Notes

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-2266), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.