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Fencer Intel
medium 6.9

CVE-2025-27371 json

In certain IETF OAuth 2.0-related specifications, when the JSON Web Token Profile for OAuth 2.0 Client Authentication mechanism is used, th…

published last yr. modified 4mo ago also EUVD-2025-5567

cvss
6.9
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 28%
public exploits
0
none known

Summary

In certain IETF OAuth 2.0-related specifications, when the JSON Web Token Profile for OAuth 2.0 Client Authentication mechanism is used, there are ambiguities in the audience values of JWTs sent to authorization servers. The affected RFCs may include RFC 7523, and also RFC 7521, RFC 7522, RFC 9101 (JAR), and RFC 9126 (PAR).

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last yr.

Exploit prediction

0.35% chance of exploitation in the next 30 days, higher than 28% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 6.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:N

Affected products

  • IETF RFC 7523

Classification

Weakness
  • CWE-305 Authentication Bypass by Primary Weakness

References

Sources

Fencer Intel 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.