GitHub Enterprise Server vulnerabilities

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.

A server-side request forgery (SSRF) vulnerability was identified in the notebook viewer of GitHub Enterprise Server. The notebook viewer validated the scheme and host of a user-supplied URL but did not validate the port, allowing requests to be directed to internal services listening on other ports of the same appliance. Response bodies were not returned to the requester, but response timing acted as an oracle that allowed instance secrets to be extracted character by character. An extracted secret could then be used in a separate interaction with an internal service to obtain remote code execution on the appliance. Exploitation required network access to the instance and was unauthenticated when private mode was disabled, or required any authenticated user when private mode was enabled. This vulnerability affected GitHub Enterprise Server versions 3.17 through 3.22 and was fixed in versions 3.22.1, 3.21.6, 3.20.8, 3.19.12, 3.18.15, and 3.17.21. This vulnerability was reported through the GitHub Bug Bounty program.

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.

A Server-Side Request Forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that allowed a repository contributor to cause the appliance to issue requests to attacker-controlled internal hosts, which could be chained to achieve remote code execution on the appliance. The secret scanning validator for GCP service account credentials trusted the token endpoint embedded in a committed credential and issued a request to it without restricting the destination. Exploitation required an authenticated user with permission to push to a repository on an instance with GitHub Advanced Security and secret scanning validity checks enabled, a non-default configuration. This vulnerability affected GitHub Enterprise Server 3.20, 3.21, and 3.22 and was fixed in versions 3.20.9, 3.21.7, and 3.22.2. This vulnerability was reported through the GitHub Bug Bounty program.

A missing authorization vulnerability in GitHub Enterprise Server allowed a repository collaborator with write access to delete the current default branch via the GraphQL API and cause an attacker-controlled branch to become the new default. In repositories requiring pull-request review but not restricting branch deletion, this bypassed the review requirement and caused fresh clones and default-branch API requests to use attacker-controlled content.

A stored cross-site scripting (XSS) vulnerability was identified in GitHub Enterprise Server that allowed an authenticated attacker to inject arbitrary HTML attributes into rendered Markdown because the Markdown rendering pipeline rewrote quote characters in already-sanitized HTML without re-sanitizing the result. Crafted Markdown could abuse same-origin JavaScript gadgets to bypass Content Security Policy and gain control of the page DOM when viewed by another user.

An authorization bypass vulnerability was identified in GitHub Enterprise Server that allowed any authenticated user of the instance to read the raw diff or patch of pull requests in private repositories without authorization. Access tokens for raw pull request diffs and patches were scoped to the repository name and pull request number rather than to a globally unique repository identifier, so an attacker who created a repository and pull request matching a target's repository name and pull request number could use a token for their own repository to retrieve the private pull request's contents. Exploitation required the attacker to know the target repository's name and a valid pull request number. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.22 and was fixed in versions 3.17.21, 3.18.15, 3.19.12, 3.20.8, and 3.21.6. This vulnerability was reported via the GitHub Bug Bounty program.

A Server-Side Request Forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that allowed remote code execution on the instance. Insufficient network isolation allowed malicious pre-receive hook code to impersonate an internal service and redirect trusted internal requests to a privileged service, leading to elevated code execution. Exploitation required pre-receive hook networking to be enabled and either site administrator privileges or write access to a repository containing a configured pre-receive hook. This vulnerability affected all versions prior to 3.22 and was fixed in versions 3.17.20, 3.18.14, 3.19.11, 3.20.7, and 3.21.5.

A time-of-check time-of-use race condition vulnerability was identified in GitHub Enterprise Server that allowed remote code execution. Exploitation required an authenticated user with write access to a repository and precise timing of concurrent upload requests. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.22 and was fixed in versions 3.17.20, 3.18.14, 3.19.11, 3.20.7, and 3.21.5.

A server-side request forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that allowed an unauthenticated attacker to cause the Manage API to send crafted outbound requests to an attacker-controlled host. The HMAC token authenticated only a timestamp, not the request path or body, so an attacker positioned to intercept the outbound request could capture and replay it against privileged management agent endpoints. High-availability deployments were not affected due to a topology restriction.

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 path traversal vulnerability was found in GitHub Enterprise Server within the Dependabot updater container. An attacker with code execution in that container could write files to arbitrary repository paths, including GitHub Actions workflow files, potentially leading to secret theft.

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.

GitHub Enterprise Server before versions 3.20.3, 3.19.7, 3.18.10, 3.17.16, and 3.16.19 has an SSRF vulnerability in the security advisories package lookup feature. An attacker can direct requests to internal services and infer sensitive environment variables, including signing secrets and private keys, via response timing.

An improper neutralization of input vulnerability was identified in GitHub Enterprise Server that allowed user-supplied HTML to inject DOM elements with IDs that collided with server-initialized data islands. These collisions could overwrite or shadow critical application state objects used by certain Project views, leading to unintended server-side POST requests or other unauthorized backend interactions. Successful exploitation requires an attacker to have access to the target GitHub Enterprise Server instance and to entice a privileged user to view crafted malicious content.

A privilege escalation vulnerability was identified in GitHub Enterprise Server that allowed an authenticated Enterprise admin to gain root SSH access to the appliance by exploiting a symlink escape in pre-receive hook environments. By crafting a malicious repository and environment, an attacker could replace system binaries during hook cleanup and execute a payload that adds their own SSH key to the root user's authorized keys. This vulnerability affected all versions prior to 3.19 and was fixed in versions 3.14.20, 3.15.15, 3.16.11, 3.17.8, 3.18.2.