Medium
liboauth2 — security advisory
In liboauth2 the Demonstrating Proof-of-Possession (DPoP) verifier accepts a proof whose JSON Web Key (jwk) header contains private key material. RFC 9449 section 4.3 step 7 requires the verifier to reject such a proof but oauth2_token_verify() function returns success for a malformed DPoP proof that embeds the private Elliptic Curve (EC) key in the header. This issue was fixed in version 2.3.0
- Products
- liboauth2
- Affected versions
- 1.4.0.1-1, 1.4.3.2-1, 1.4.3.2-2, 1.4.3.2-3, 1.4.3.2-3ubuntu1, 1.4.3.2-4, 1.4.4-1, 1.5.1-3, 1.5.2-1, 1.6.0-1, 1.6.0-1build1, 1.6.0-1build3, 1.6.0-1build4, 2.1.0-1, 2.1.0-2, 2.1.1-1, 2.2.0-1, 2.2.0-2ubuntu1, 2.4.0-1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-54431
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:46 UTC · Revision 1
Source evidence
In liboauth2 the Demonstrating Proof-of-Possession (DPoP) verifier accepts a proof whose JSON Web Key (jwk) header contains private key material. RFC 9449 section 4.3 step 7 requires the verifier to reject such a proof but oauth2_token_verify() function returns success for a malformed DPoP proof that embeds the private Elliptic Curve (EC) key in the header. This issue was fixed in version 2.3.0
osv:UBUNTU-CVE-2026-54431
liboauth2
Fixed versions: Not specified
liboauth2
Fixed versions: Not specified
liboauth2
Fixed versions: Not specified
liboauth2
Fixed versions: Not specified
liboauth2
Fixed versions: Not specified
Complete source record
{
"id": "f3c75126e2d24725febe4df9abbec251dc88d8cdd782b91dec3c752d7a827522",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-54431",
"method": "structured",
"payload": {
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"title": "UBUNTU-CVE-2026-54431",
"summary": "In liboauth2 the Demonstrating Proof-of-Possession (DPoP) verifier accepts a proof whose JSON Web Key (jwk) header contains private key material. RFC 9449 section 4.3 step 7 requires the verifier to reject such a proof but oauth2_token_verify() function returns success for a malformed DPoP proof that embeds the private Elliptic Curve (EC) key in the header. This issue was fixed in version 2.3.0",
"evidence": "osv:UBUNTU-CVE-2026-54431",
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"aliases": [
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{
"type": "Ubuntu",
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"affected": [
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],
"modified": "2026-10-17T12:59:06.459516642Z",
"provider": "osv",
"upstream": [
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],
"references": [
"https://ubuntu.com/security/CVE-2026-54431",
"https://www.cve.org/CVERecord?id=CVE-2026-54431",
"https://cert.pl/en/posts/2026/07/CVE-2026-54430",
"https://github.com/OpenIDC/liboauth2",
"https://github.com/OpenIDC/liboauth2/commit/c0b57152ed6a0af33aeb04a60bd7f5bff5ab8800"
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},
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"source_id": "core-osv",
"document_id": 359300,
"published_at": "2026-07-02T11:16:00+00:00"
}