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🛡️ CVE-2026-25138 — rucio

🟡 CVSS 5.3 — Medium ⚠️ Exploit Public CWE-204 NVD
5.3
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Rucio WebUI has Username Enumeration via Login Error Message

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:

```

Cannot get find any account associated with 15251087 identity.

```

Bogus Login (Existing Username "root", Wrong Password)

Response contains:

```

Cannot get auth token. It is possible that the presented identity root is not mapped to any Rucio account root.

```

The difference in error messages confirms whether a username exists.

Impact

An unauthenticated attacker can enumerate valid usernames, which may be leveraged for targeted password guessing, credential stuffing, or social engineering attacks.

Remediation / Mitigation

Return a generic authentication failure message for all login errors, regardless of whether the username exists. Avoid disclosing account or identity existence through error responses. Consider implementing rate limiting or additional login throttling to further reduce abuse.

Reources:

  • OWASP Authentication Cheat Sheet - Authentication and Error Messages: https://cheatsheetseries.owasp.org/cheatsheets/Authentication_Cheat_Sheet.html#authentication-and-error-messages

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity none, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: Low — limited, and the attacker does not choose what is affected.
  • Integrity impact: None.
  • Availability impact: None.

Weakness class

CVE-2026-25138 is classified as CWE-204: Observable Response Discrepancy. The product provides different responses to incoming requests in a way that reveals internal state information to an unauthorized actor outside of the intended control sphere.

Affected software

CVE-2026-25138 is recorded against 2 packages.

  • rucio (from 39.0.0 up to 39.3.1)
  • rucio-webui (from 39.0.0rc1 up to 39.3.1)

Timeline and source

Published on 25 February 2026 and last revised on 17 June 2026. A public exploit is known to exist, which raises the urgency of patching considerably. Record sourced from NVD.

References

cheatsheetseries.owasp.org
github.com
github.com
github.com
github.com
github.com

Other advisories for this package

rucio has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-204: Observable Response Discrepancy) in other software:

Details

Severity MEDIUM
CVSS Score 5.3
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CWE CWE-204
Public Exploit ⚠️ Yes
Source NVD
Published 2026-02-25
Updated 2026-08-20
Modified 2026-06-17
Fix URL N/A

Affected Packages

Software From version Fixed in
rucio 39.0.0 39.3.1
rucio-webui 39.0.0rc1 39.3.1

Similar Threats

Exploit Protection

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