CVE-2026-13089Network attack vector

Authentication bypass via token-controlled algorithm allowlist

Published Jul 22, 2026 · Updated Jul 22, 2026

Signature verification bypass in Ryo Ito OIDC::Lite 0 through 0.12.1 allows remote attackers to forge ID Tokens via unpinned algorithms. OIDC::Lite::Model::IDToken::verify copies the token header's alg value into JSON::WebToken's accepted-algorithm list, permitting unsigned tokens or RSA-to-HMAC key confusion. The flaw is reachable when an application omits an explicit algorithm, allowing attacker-chosen identity claims to authenticate as another user.

CVSS severity7.5
High
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Signature verification bypass in Ryo Ito OIDC::Lite 0 through 0.12.1 allows remote attackers to forge ID Tokens via unpinned algorithms. OIDC::Lite::Model::IDToken::verify copies the token header's alg value into JSON::WebToken's accepted-algorithm list, permitting unsigned tokens or RSA-to-HMAC key confusion. The flaw is reachable when an application omits an explicit algorithm, allowing attacker-chosen identity claims to authenticate as another user.

The record

CVE
CVE-2026-13089
Published
Jul 22, 2026
Updated
Jul 22, 2026
Vendor
Ryo Ito
Product
OIDC::Lite
Classifications
CWE-347
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 22, 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 <=0.12.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Ryo Ito · OIDC::Liteversion=0 <=0.12.1

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A: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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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