# CVE-2026-2266: Improper neutralization of input vulnerability was identified in GitHub Enterprise Server that allowed cross-site scripting via task list content and enabled arbitrary HTML injection

> CVE-2026-2266: Improper neutralization of input vulnerability was identified in GitHub Enterprise Server that allowed cross-site scripting via task list content and enabled arbitrary HTML injection. CVSS 5.4 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-2266
Last updated: 2026-06-17T10:30:40Z

- Published: 2026-03-10 18:55 UTC · Updated: 2026-06-17 10:30 UTC · Assigner: GitHub\_P
- CVSS: 5.4 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
- EPSS: 0.18%, 8th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-79

## 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.

## Affected vendors and products

- GitHub: Enterprise Server

## Tracked companies

- [GitHub](https://rewindex.com/company/github.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-2266)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-2266)
- [https://docs.github.com/en/enterprise-server@3.18/admin/release-notes\#3.18.6](https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.6)
- [https://docs.github.com/en/enterprise-server@3.19/admin/release-notes\#3.19.3](https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.3)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-2266 · Markdown: https://rewindex.com/cve/CVE-2026-2266.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-2266 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:11:32.343Z