When the caller does not pin an algorithm, OIDC::Lite::Model::IDToken::verify sets $self->alg($self->header->{alg}) from the token's own header and then calls decode_jwt(token, key, 1, [$self->alg]), handing JSON::WebToken an accepted-algorithm allowlist taken from the untrusted token. A token with alg=none yields ['none'], so decode_jwt returns the claims with no signature check, and a token with alg=HS256 is verified with the RP's RSA public key as the HMAC secret (RS to HS confusion).
The ID Token is the OpenID Connect authentication assertion delivered to the Relying Party. Any caller that verifies an ID Token through the unpinned load(token)->verify path, or load(token, key) with only the key pinned, accepts a forged token carrying attacker-chosen claims such as sub and is authenticated as any user. Passing an explicit algorithm so $self->alg is already set bypasses the header-derived allowlist and is not affected.
Note that the latest version uploaded to CPAN is 0.10. Later versions are available in the git repository.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| RITOU | OIDC::Lite | unaffected |
|
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Solution
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Workaround
Apply the patch. Otherwise, pin the expected signature algorithm at the call site, for example OIDC::Lite::Model::IDToken->load($token, $key, $alg) with an explicit non-none $alg, so verify uses the pinned algorithm instead of the value in the token header.
Wed, 22 Jul 2026 21:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | OIDC::Lite versions through 0.12.1 for Perl allow ID Token signature verification bypass via a token-controlled algorithm allowlist in verify. When the caller does not pin an algorithm, OIDC::Lite::Model::IDToken::verify sets $self->alg($self->header->{alg}) from the token's own header and then calls decode_jwt(token, key, 1, [$self->alg]), handing JSON::WebToken an accepted-algorithm allowlist taken from the untrusted token. A token with alg=none yields ['none'], so decode_jwt returns the claims with no signature check, and a token with alg=HS256 is verified with the RP's RSA public key as the HMAC secret (RS to HS confusion). The ID Token is the OpenID Connect authentication assertion delivered to the Relying Party. Any caller that verifies an ID Token through the unpinned load(token)->verify path, or load(token, key) with only the key pinned, accepts a forged token carrying attacker-chosen claims such as sub and is authenticated as any user. Passing an explicit algorithm so $self->alg is already set bypasses the header-derived allowlist and is not affected. Note that the latest version uploaded to CPAN is 0.10. Later versions are available in the git repository. | |
| Title | OIDC::Lite versions through 0.12.1 for Perl allow ID Token signature verification bypass via a token-controlled algorithm allowlist in verify | |
| Weaknesses | CWE-347 | |
| References |
|
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MITRE
Status: PUBLISHED
Assigner: CPANSec
Published:
Updated: 2026-07-22T22:21:41.686Z
Reserved: 2026-06-23T18:53:35.254Z
Link: CVE-2026-13089
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