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CVE-2024-32657· NVD / CVE Program· CNA GitHub_M

Hydra has persistent XSS vulnerability serving HTML build outputs

Hydra is a Continuous Integration service for Nix based projects. Attackers can execute arbitrary code in the browser context of Hydra and execute authenticated HTTP requests. The abused feature allows Nix builds to specify files that Hydra serves to clients. One use of this functionality is serving NixOS `.iso` files. The issue is only with html files served by Hydra. The issue has been patched on https://hydra.nixos.org around 2024-04-21 14:30 UTC. The nixpkgs package were fixed in unstable and 23.11. Users with custom Hydra packages can apply the fix commit to their local installations. The vulnerability is only triggered when opening HTML build artifacts, so not opening them until the vulnerability is fixed works around the issue.

MediumCVSS 5.4 · v3.1—No exploit No fix recorded
Published
Apr 22, 2024
Updated
Jun 17, 2026
EPSS
0.5% · 38th percentile
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Report tools

JSON

Action score

21

Monitor

Low priority for now.

CVSS
21 / 40 · 5.4 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
5.4
CNA · GitHub_M
4.6
0.8 point gap

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Noroxi analysis

No Noroxi analysis for this record yet

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Affected systems

VendorProduct
nixoshydra

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • nixos hydrabefore 23.11

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • NixOS hydra

    • < b72528be5074f3e62e9ae2c2ae8ef9c07a0b4dd3, < 23.11affected

Same product

nixos: all records

Other highest-scoring records for the same primary product.

  • CVE-2024-45049Nix Hydra Missing authentication when triggering evaluations
    30Monitor
  • CVE-2025-54800Hydra persistent XSS in build metrics
    28Monitor
  • CVE-2025-54864Hydra missing authentication when triggering evaluations through GitHub and Gitea plugins
    27Monitor
  • CVE-2025-32435Hydra no restricted eval after nix-eval-jobs migration
    10Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2025-54800477 days apartHydra persistent XSS in build metrics
    28Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

  • CVE-2024-45049127 days apartNix Hydra Missing authentication when triggering evaluations
    30Monitor

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
low · data can be read
Integrity
low · data or configuration can be modified
Availability
none

Impact can extend beyond the vulnerable component (scope changes).

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
Required
Scope
Changed
Confidentiality impact
Low
Integrity impact
Low
Availability impact
None

Weakness class (CWE)

CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

nvd-primary

Root cause

User content is inserted into the page as HTML. The browser interprets the content as code rather than data.

The bug in code

The whole CWE-79 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
commentEl.innerHTML = comment.body;

Fixed

ts
commentEl.textContent = comment.body;

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records