QSearchQSearch

CVE-2026-42790

8.1 HIGH

Improper Certificate Validation vulnerability in Erlang OTP public_key (pubkey_cert and public_key modules) allows a DNS nameConstraints ...

Published: 2026-05-27 · Last updated: 2026-06-02

Severity and scoring

CVSS
8.1 HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
CWE
CWE-295, CWE-297

Affected products

VendorProduct
erlangerlang\/otp

Description

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.

Source: NVD

References

Related CVEs

Same vendor

  • CVE-2026-42791 — Improper Certificate Validation vulnerability in Erlang OTP public_key (pubkey_ocsp module) allows forged OCSP responses signed with an e... (3.7 LOW)
  • CVE-2026-42789 — Improper Following of a Certificate's Chain of Trust vulnerability in Erlang OTP public_key (pubkey_cert module) allows a non-CA certific... (4.8 MEDIUM)
  • CVE-2026-32147 — Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in Erlang OTP ssh (ssh_sftpd module) allows ... (4.3 MEDIUM)
  • CVE-2026-23943 — Improper Handling of Highly Compressed Data (Compression Bomb) vulnerability in Erlang OTP ssh (ssh_transport modules) allows Denial of S... (5.3 MEDIUM)
  • CVE-2026-23942 — Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in Erlang OTP (ssh_sftpd module) allows Path... (5.4 MEDIUM)

Same CWE

  • CVE-2026-53475 — A flaw was found in assisted-migration-agent (9.3 CRITICAL)
  • CVE-2026-9758 — Improper comparison with the certificates trusted list in S2OPC allows an attacker well-formed untrusted certificate to be considered tru... (7.3 HIGH)
  • CVE-2026-41714 — Applications that configure their broker connection via RabbitConnectionFactoryBean.setUri("amqps://...") without also calling setUseSSL(... (4.0 MEDIUM)
  • CVE-2026-42769 — Issue Summary: An error in the callback used to verify the certificate provided in a Root CA key update Certificate Management Protocol (... (5.3 MEDIUM)
  • CVE-2026-50752 — A weakness in the certificate validation logic of the deprecated IKEv1 key exchange may allow an unauthenticated attacker positioned as a... (7.4 HIGH)