CVE-2026-54431Public exploit

Malformed DPoP proof acceptance via private JWK

Published Jul 2, 2026 · Updated Jul 2, 2026

Improper DPoP validation in OpenIDC liboauth2 before 2.3.0 allows local users to have proofs containing private EC keys accepted. The _oauth2_dpop_parse_and_validate() path parsed the jwk header without rejecting private members, so oauth2_token_verify() returned success. Reachability requires local access to a caller of the library's verifier; the published record identifies malformed-proof acceptance but no broader consequence.

CVSS severity5.1
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper DPoP validation in OpenIDC liboauth2 before 2.3.0 allows local users to have proofs containing private EC keys accepted. The _oauth2_dpop_parse_and_validate() path parsed the jwk header without rejecting private members, so oauth2_token_verify() returned success. Reachability requires local access to a caller of the library's verifier; the published record identifies malformed-proof acceptance but no broader consequence.

The record

CVE
CVE-2026-54431
Published
Jul 2, 2026
Updated
Jul 2, 2026
Vendor
OpenIDC
Product
liboauth2
Classifications
CWE-358
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 2, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 2, 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=0 <2.3.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

OpenIDC · liboauth2version=0 <2.3.0

Published CVSS scores

5.1CERT.PLCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA: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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-358Improperly Implemented Security Check for Standard

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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