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Fencer Intel
critical 9.1

CVE-2026-63687 json

Apache CXF: JwtRequestCodeFilter silently overrides outer PKCE and nonce parameters

published 3mo ago modified 18d ago also EUVD-2026-53860

cvss
9.1
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

Apache CXF's JwtRequestCodeFilter copies all claims from a signed request JWT into the authorization parameter map without excluding security-sensitive parameters. A client that can produce a validly-signed request JWT (e.g., one whose client_secret is known or compromised) can thereby substitute the code_challenge, code_challenge_method, nonce, and state values that were set in the outer HTTP request, undermining PKCE integrity and OpenID Connect replay protection. Users are recommended to upgrade to versions 4.2.3 or 4.1.8 or 3.6.12, which fix this issue.

Patch / fix

  • Apache Software Foundation Apache CXF 3.6.12, 4.1.8, 4.2.3

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-63687 updated cvss 7.1

cxf-rt-rs-security-oauth2: Apache CXF: Security bypass due to improper handling of authorization parameters

  • Red Hat Fuse 7 cxf-rt-rs-security-oauth2
    affected: workaround, no fix planned “Will not fix”
  • Red Hat JBoss Enterprise Application Platform 7 cxf Red Hat JBoss Web Server 5 cxf-rt-rs-security-oauth2
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat build of Apache Camel 4.18.4 for Spring Boot 3.5.16
    fixed: vendor fix RHSA-2026:71675

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
3mo ago

Exploit prediction

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

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 CXF

Classification

Weakness
  • CWE-345 Insufficient Verification of Data Authenticity

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.