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Fencer Vulns
critical 9.1

CVE-2026-87785 json

Apache Syncope: JWT subject spoofing

published 2026-09-14 55 d ago modified 2026-09-14 55 d ago also EUVD-2026-77368

cvss
9.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 46%
public exploits
0
none known

Summary

Authentication bypass by spoofing vulnerability in Apache Syncope.

When the configured JWKS settings for internal JWT authentication are disclosed (at least protocol and key), an attacker can spoof another user's privileges after completing a successful authentication and obtaining a valid JWT.

This issue affects Apache Syncope: from 3.0.0-M0 through 3.0.16, from 4.0.0-M0 through 4.0.7, from 4.1.0-M0 through 4.1.2.

Users are recommended to upgrade to version 4.0.8 / 4.1.3, which fix this issue.

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
55 d ago

Exploit prediction

0.55% chance of exploitation in the next 30 days, higher than 46% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CNA 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

  • Apache Software Foundation Apache Syncope

Classification

Weakness
  • CWE-290 Authentication Bypass by Spoofing

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.