CVE-2026-25138Public exploitNetwork attack vector

Username enumeration via distinct login errors

Published Feb 25, 2026 · Updated Feb 25, 2026

Observable response discrepancy in affected Rucio WebUI releases allows remote attackers to enumerate valid usernames through the login endpoint. The /ui/login handler returns an account-association error for an unknown identity but a different authentication error for a valid identity with a wrong password. No authentication or user interaction is required; response comparison discloses account existence and supports targeted password guessing or credential stuffing.

CVSS severity5.3
Medium
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Observable response discrepancy in affected Rucio WebUI releases allows remote attackers to enumerate valid usernames through the login endpoint. The /ui/login handler returns an account-association error for an unknown identity but a different authentication error for a valid identity with a wrong password. No authentication or user interaction is required; response comparison discloses account existence and supports targeted password guessing or credential stuffing.

The record

CVE
CVE-2026-25138
Published
Feb 25, 2026
Updated
Feb 25, 2026
Vendor
Rucio
Product
Rucio
Classifications
CWE-204, T1589.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 25, 2026Record 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=< 35.8.3
  2. Affected versionversion=>= 36.0.0rc1, < 38.5.4
  3. Affected versionversion=>= 39.0.0rc1, < 39.3.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Rucio · Rucioversion=< 35.8.3; version=>= 36.0.0rc1, < 38.5.4; version=>= 39.0.0rc1, < 39.3.1

Published CVSS scores

5.3GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-204Observable Response Discrepancy
T1589.001Gather Victim Identity Information: Credentials

Public exploit references

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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