CVE-2026-2266 Cross-site scripting in Enterprise Server
An authenticated attacker can inject arbitrary HTML and execute scripts in other users' browsers via malicious task list items in GitHub Enterprise Server.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-2266?
CVE-2026-2266 is a high-severity cross-site scripting vulnerability in Github Enterprise Server, published on 10 Mar 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-79
Which versions are affected by CVE-2026-2266?
It affects 1 product.
Products include Github Enterprise Server.
How do I fix CVE-2026-2266?
No fix has been published for CVE-2026-2266 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-2266 being exploited?
There is no known exploitation of CVE-2026-2266 in the wild and no public exploit code.
Other vulnerabilities in Github Enterprise Server
- CVE-2024-4985 Auth bypass in Enterprise Server
- CVE-2022-23739 Missing authorization in GitHub Enterprise Server
- CVE-2022-46255 Improper Limitation of a Pathname to a Restricted Directory in GitHub Enterprise Server leading to RCE
- CVE-2021-22869 Improper access control in GitHub Enterprise Server allows self-hosted runners to execute outside their control group
- CVE-2024-9487 Auth bypass in Enterprise Server
Sources
Also known as GHSA-vg33-x66f-82h4.