What’s Vulnerable › Vulnerabilities

CVE-2026-25138: Rucio WebUI has Username Enumeration via Login Error Message

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-02-25 · updated 2026-06-17
• Weakness: CWE-204

Description

Rucio is a software framework that provides functionality to organize, manage, and access large volumes of scientific data using customizable policies. Prior to versions 35.8.3, 38.5.4, and 39.3.1, the WebUI login endpoint returns distinct error messages depending on whether a supplied username exists, allowing unauthenticated attackers to enumerate valid usernames. Versions 35.8.3, 38.5.4, and 39.3.1 fix the issue.

Affected products

• rucio: before 35.8.3; from 36.0.0 before 38.5.4; from 39.0.0 before 39.3.1 — fixed in 35.8.3, 38.5.4, 39.3.1

How to fix

Upgrade to a fixed version: rucio 35.8.3, 38.5.4, 39.3.1. Check the vendor advisory for mitigations.

References

• https://cheatsheetseries.owasp.org/cheatsheets/Authentication_Cheat_Sheet.html#authentication-and-error-messages
• https://github.com/rucio/rucio/releases/tag/35.8.3
• https://github.com/rucio/rucio/releases/tag/38.5.4
• https://github.com/rucio/rucio/releases/tag/39.3.1
• https://github.com/rucio/rucio/security/advisories/GHSA-38wq-6q2w-hcf9
• https://github.com/rucio/rucio/security/advisories/GHSA-38wq-6q2w-hcf9

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