Rucio WebUI has Username Enumeration via Login Error Message

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-25138: 0.38% estimated exploitation activity in the next 30 days; percentile 31.57 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The WebUI login endpoint returns distinct error messages depending on whether a supplied username exists, allowing unauthenticated attackers to enumerate valid usernames. Details When submitting invalid credentials to /ui/login, the WebUI responds with different error messages based on the existence of the provided username (identity). A non-existent username results in an error indicating that no account is associated with the identity, while an existing username with an incorrect password produces a different authentication-related error. This behavioral difference allows an attacker to distinguish valid usernames from invalid ones by observing the response content. Proof of Concept Bogus Login (Non-existent Username "15251087") Response contains: Bogus Login (Existing Username "root", Wrong Password) Response contains: The difference in error messages confirms whether a username exists. Impact An unauthenticated attacker can enumerate valid usernames, which may be…

Published by the source

25 Feb 2026, 18:53 UTC

Last modified by the source

13 Jul 2026, 16:42 UTC

Source last checked

26 Oct 2026, 13:36 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-38wq-6q2w-hcf9

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-38wq-6q2w-hcf9

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# Patch Next advisory brief: CVE-2026-25138

Advisory: Rucio WebUI has Username Enumeration via Login Error Message
IDs: CVE-2026-25138, GHSA-38wq-6q2w-hcf9
Record: https://patchnext.com/advisories/cve-2026-25138 (revision 2, source checked 26 Oct 2026, 13:36 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: rucio-webui 39.3.1, 38.5.4, 35.8.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI rucio-webui: affected < 35.8.3; >= 36.0.0rc1, < 38.5.4; >= 39.0.0rc1, < 39.3.1; fixed in 39.3.1, 38.5.4, 35.8.3

## Suggested inspection (read-only)
- `python -m pip show rucio-webui`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on rucio-webui.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-38wq-6q2w-hcf9 (OSV record GHSA-38wq-6q2w-hcf9 lists affected ranges: PyPI rucio-webui >=0 =36.0.0rc1 =39.0.0rc1 <39.3.1 (fixed))
- Verified: https://github.com/advisories/GHSA-38wq-6q2w-hcf9 (GitHub-reviewed advisory GHSA-38wq-6q2w-hcf9 lists affected ranges: PyPI rucio-webui >=0 =36.0.0rc1 =39.0.0rc1 <39.3.1)

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