Lookup for vulnerabilities affecting packages.
| Vulnerability_id | VCID-wsby-unw4-zqe7 |
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| Summary | Improper Certificate Validation vulnerability in Erlang OTP public_key (pubkey_cert and public_key modules) allows a DNS nameConstraints bypass via subject CommonName fallback in TLS hostname verification. Two flaws combine to allow a subordinate CA whose DNS nameConstraints are restricted (e.g. permitted;DNS:allowed.example.com) to issue a leaf certificate that an OTP TLS client accepts as a valid identity for an out-of-scope hostname (e.g. victim.example.com): First, pubkey_cert:validate_names/6 in lib/public_key/src/pubkey_cert.erl only checks SAN DNS entries against nameConstraints. Per RFC 5280, a permitted DNS subtree only restricts certificates that contain a DNS-typed name. A leaf with no subjectAltName therefore trivially satisfies any permitted;DNS:... constraint regardless of its subject commonName. Second, public_key:pkix_verify_hostname/3 in lib/public_key/src/public_key.erl falls back to the subject commonName when no subjectAltName is present, extracting id-at-commonName attributes as presented IDs and matching them against the reference hostname. The strict pkix_verify_hostname_match_fun(https) matcher does not suppress this fallback. The result is that path validation accepts a CN-only leaf under a DNS-constrained intermediate (no SAN means the nameConstraints are not triggered), and hostname verification then accepts it via the CN fallback. The bypass is reachable from stock ssl:connect with verify_peer, a trusted CA, SNI, and the canonical strict https hostname matcher. This issue affects OTP from OTP 19.3 before OTP 26.2.5.21, 27.3.4.12, 28.5.0.1, and 29.0.1 corresponding to public_key from 1.4 before 1.15.1.7, 1.17.1.3, 1.20.3.1, and 1.21.1. |
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| Weaknesses |
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| cwe_id |
295 |
| name |
Improper Certificate Validation |
| description |
The product does not validate, or incorrectly validates, a certificate. |
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| 1 |
| cwe_id |
297 |
| name |
Improper Validation of Certificate with Host Mismatch |
| description |
The product communicates with a host that provides a certificate, but the product does not properly ensure that the certificate is actually associated with that host. |
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| Exploits |
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| Severity_range_score | 7.4 - 7.6 |
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| Exploitability | 0.5 |
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| Weighted_severity | 0.0 |
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| Risk_score | null |
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| Resource_url | http://public2.vulnerablecode.io/vulnerabilities/VCID-wsby-unw4-zqe7 |
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