Enterprise Server: URL Redirection to Untrusted Site
CVE-2026-0573 is a critical-severity URL redirection to untrusted site vulnerability in Enterprise Server from GitHub, with a CVSS 3.1 base score of 9.0 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, but only if a user takes part, for example by opening a link or file. Affected Enterprise Server versions: 3.14 through 3.14.21; 3.15 through 3.15.16; 3.16 through 3.16.12, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.73% chance of exploitation within 30 days, higher than 55% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of Enterprise Server you run against the affected versions below, and install the vendor's latest release.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| GitHub | Enterprise Server | 3.14 through 3.14.21; 3.15 through 3.15.16; 3.16 through 3.16.12; 3.17 through 3.17.9; 3.18 through 3.18.3; 3.19 through 3.19.1 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 7.6 | High | CNA (github.com) |
| CVSS 3.1 | 9.0 | Critical | NVD |
Official description
An URL redirection vulnerability was identified in GitHub Enterprise Server that allowed attacker-controlled redirects to leak sensitive authorization tokens. The repository_pages API insecurely followed HTTP redirects when fetching artifact URLs, preserving the authorization header containing a privileged JWT. An authenticated user could redirect these requests to an attacker-controlled domain, exfiltrate the Actions.ManageOrgs JWT, and leverage it for potential remote code execution. Attackers would require access to the target GitHub Enterprise Server instance and the ability to exploit a legacy redirect to an attacker-controlled domain. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.19 and was fixed in versions 3.19.2, 3.18.4, 3.17.10, 3.16.13, 3.15.17, and 3.14.22. This vulnerability was reported via the GitHub Bug Bounty program.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: URL Redirection to Untrusted Site
The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.
How developers prevent this class of flaw
- Use an intermediate disclaimer page that provides the user with a clear warning that they are leaving the current site. Implement a long timeout before the redirect occurs, or force the user to click on the link. Be careful to avoid XSS problems (CWE-79) when generating the disclaimer page.
- When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs. For example, ID 1 could map to /login.asp and ID 2 could map to http://www.example.com/. Features such as the ESAPI AccessReferenceMap provide this capability.
- Ensure that no externally-supplied requests are honored by requiring that all redirect requests include a unique nonce generated by the application. Be sure that the nonce is not predictable (CWE-330).
More URL Redirection to Untrusted Site vulnerabilities (CWE-601)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- docs.github.com/en/[email protected]/admin/release-notes#3.14.22Product, Release Notes
- docs.github.com/en/[email protected]/admin/release-notes#3.15.17Product, Release Notes
- docs.github.com/en/[email protected]/admin/release-notes#3.16.13Product, Release Notes
- docs.github.com/en/[email protected]/admin/release-notes#3.17.10Product, Release Notes
- docs.github.com/en/[email protected]/admin/release-notes#3.18.4Product, Release Notes
- docs.github.com/en/[email protected]/admin/release-notes#3.19.2Product, Release Notes
Other vulnerabilities in Enterprise Server
- 7.7 High severity
- 8.8 High severity
- 9.8 Critical severity
- 8.8 High severity
- 7.5 High severity
- 7.4 High severity
Recent URL Redirection to Untrusted Site vulnerabilities
- 8.1 High severity
- 7.4 High severity
- 9.8 Critical severity
- 8.6 High severity
- 8.8 High severity
- 8.8 High severity
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