CVE-2026-15343

A denial of service vulnerability was identified in GitHub Enterprise Server that allowed an unauthenticated attacker to cause service disruption by sending crafted requests with deeply nested JSON payloads to an unauthenticated API endpoint. The endpoint parsed user-controlled JSON request bodies without size or depth limits.

GitHub Enterprise Server before version 3.22 has a path traversal vulnerability that allows an unauthenticated attacker to delete arbitrary files and directories on the instance, including the entire user storage directory containing Git LFS objects, release assets, attachments, and avatars. Exploitation of the X-GitHub-Request-Id header without sanitization as a filesystem path segment leads to data deletion.

GitHub Enterprise Server prior to version 3.22 has an SSRF vulnerability in an upload endpoint that allows an unauthenticated attacker to send crafted requests to internal services. By injecting path traversal content into request parameters, an attacker can bypass the intended request flow and redirect internal API calls.

GitHub Enterprise Server before version 3.21 contains a denial of service vulnerability that allows an unauthenticated attacker to cause excessive CPU consumption and exhaust the pool of request-handling worker processes by sending a crafted form-encoded HTTP POST request with deeply nested parameters. The vulnerability was fixed in versions 3.20.3, 3.19.7, 3.18.10, and 3.17.16.

A missing authorization vulnerability in GitHub Enterprise Server allowed an authenticated user with write access to any repository to read metadata from private repositories they did not have access to. The flaw enabled enumeration of rule identifiers and disclosure of repository names, branch names, commit SHAs, commit messages, and the pushing actor.

A denial of service vulnerability in GitHub Enterprise Server allowed an authenticated user to disrupt the instance by supplying a deeply nested YAML release notes configuration file. During release notes generation, the file was parsed without a nesting depth limit, causing excessive resource consumption and rendering the instance unresponsive.

An incorrect authorization vulnerability in GitHub Enterprise Server allowed a user-to-server token scoped to a GitHub App installation to perform write operations on public repositories outside its intended scope. An attacker with a stolen token could create issues, comments, and private vulnerability reports, impersonating the victim without app involvement.

A stored cross-site scripting vulnerability was found in GitHub Enterprise Server, allowing an authenticated attacker to execute arbitrary JavaScript in another user's browser by injecting a malicious payload into the title of a Discussion in the Q&A category. The AnsweredQuestionStructuredDataComponent failed to escape user-controlled Discussion titles before embedding them in a <script type="application/ld+json"> block, enabling breakout from the script context. The attack was escalated to full XSS by leveraging JSONP callback support in the REST API to bypass Content Security Policy.

A missing authorization vulnerability in GitHub Enterprise Server allowed an authenticated user to read source code from private repositories they did not have access to via the Copilot pull request description diff summary endpoint. The vulnerability affects all versions prior to 3.21 and was fixed in versions 3.17.17, 3.18.11, 3.19.8, and 3.20.4.

A UI misrepresentation vulnerability in GitHub Enterprise Server allowed an OAuth application to gain unintended access to an organization's runner management. The issue occurred because the manage_runners:org scope was not displayed on the authorization consent screen, enabling an attacker to trick a user into authorizing a malicious app.