CVE-2025-54800Network attack vector

Persistent XSS via unescaped build output metadata

Published Aug 12, 2025 · Updated Aug 12, 2025

Stored cross-site scripting in NixOS Hydra before commit dea1e16 allows remote attackers to run JavaScript through malicious build metadata. Hydra stores unvalidated names, units, and release data from nix-support output files and embeds those values unescaped in build-page templates. A third-party project must supply the metadata and a user, including an administrator, must visit the affected build page, allowing the script to act in that browser context.

CVSS severity7.1
High
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in NixOS Hydra before commit dea1e16 allows remote attackers to run JavaScript through malicious build metadata. Hydra stores unvalidated names, units, and release data from nix-support output files and embeds those values unescaped in build-page templates. A third-party project must supply the metadata and a user, including an administrator, must visit the affected build page, allowing the script to act in that browser context.

The record

CVE
CVE-2025-54800
Published
Aug 12, 2025
Updated
Aug 12, 2025
Vendor
NixOS
Product
Hydra
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 12, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 12, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< dea1e168f590efb27db32dbacc82b09e15f8ae4b

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

NixOS · Hydraversion=< dea1e168f590efb27db32dbacc82b09e15f8ae4b

Published CVSS scores

7.1GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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