What’s Vulnerable › Vulnerabilities

CVE-2025-54800: Hydra persistent XSS in build metrics

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-08-12 · updated 2026-06-17
• Weakness: CWE-79

Description

Hydra is a continuous integration service for Nix based projects. Prior to commit dea1e16, a malicious package can introduce arbitrary JavaScript code into the Hydra database that is automatically evaluated in a client's browser when anyone visits the build page. This could be done by a third-party project as part of its build process. This also happens in other places like with hydra-release-name. This issue has been patched by commit dea1e16. A workaround involves either not building untrusted packages or not visiting the builds page.

Affected products

• NixOS hydra: before 2025-08-12 — fixed in 2025-08-12

How to fix

Upgrade to a fixed version: NixOS hydra 2025-08-12. Check the vendor advisory for mitigations.

References

• https://github.com/NixOS/hydra/commit/dea1e168f590efb27db32dbacc82b09e15f8ae4b
• https://github.com/NixOS/hydra/security/advisories/GHSA-7qwg-q53v-vh99

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