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Fencer Vulns
medium 5.9

CVE-2025-9824 json

User Enumeration via Response Timing

published 2025-09-03 14 mo ago modified 2026-10-19 20 d ago also GHSA-3ggv-qwcp-j6xg , EUVD-2025-26524

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 20%
public exploits
0
none known

Summary

ImpactThe attacker can validate if a user exists by checking the time login returns. This timing difference can be used to enumerate valid usernames, after which an attacker could attempt brute force attacks.

PatchesThis vulnerability has been patched, implementing a timing-safe form login authenticator that ensures consistent response times regardless of whether a user exists or not.

Technical DetailsThe vulnerability was caused by different response times when:

* A valid username was provided (password hashing occurred) * An invalid username was provided (no password hashing occurred)

The fix introduces a TimingSafeFormLoginAuthenticator that performs a dummy password hash verification even for non-existent users, ensuring consistent timing.

WorkaroundsNo workarounds are available. Users should upgrade to the patched version.

References * https://owasp.org/www-project-web-security-testing-guide/latest/4-Web_Application_Security_Testing/03-Identity_Management_Testing/04-Testing_for_Account_Enumeration_and_Guessable_User_Account

Patch / fix

  • packagist mautic/core 4.4.17, 5.2.8, 6.0.5
  • Mautic Mautic < 4.4.17, < 5.2.8, < 6.0.5

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
14 mo ago

Exploit prediction

0.28% chance of exploitation in the next 30 days, higher than 20% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
packagist mautic/core
>=4.4.0, <4.4.17
>=5.0.0-alpha, <5.2.8
>=6.0.0-alpha, <6.0.5
4.4.17
5.2.8
6.0.5

Affected products

  • Mautic Mautic

Classification

Weakness
  • CWE-204 Observable Response Discrepancy

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.