Veille CVE
CVE-2026-42790
8.1 ÉlevéeDescription
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 29.0.1, OTP 28.5.0.1, OTP 27.3.4.12 and OTP 26.2.5.21, corresponding to public_key from 1.4 before 1.21.1, 1.20.3.1, 1.17.1.3 and 1.15.1.7.
Produits concernés
Scores CVSS
| Version | Score | Source | Vecteur |
|---|---|---|---|
| 4.0 | 7.6 Élevée | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
| 3.1 | 8.1 Élevée | nvd@nist.gov (NVD) | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N |
| 3.1 | 7.4 Élevée | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N |
Faiblesses (CWE)
Références
- https://cna.erlef.org/cves/CVE-2026-42790.html Third Party Advisory
- https://github.com/erlang/otp/commit/0769050c69d73762672b0db1347b6993a5b31759 Patch
- https://github.com/erlang/otp/commit/21abed64eb2026b5f82f432709e4e932f9be389a Patch
- https://github.com/erlang/otp/commit/fb67c6d1836f51105a96d8b769e71e4215a79457 Patch
- https://github.com/erlang/otp/security/advisories/GHSA-22cw-4ph4-6447 Vendor Advisory
- https://osv.dev/vulnerability/EEF-CVE-2026-42790 MitigationThird Party Advisory
- https://www.erlang.org/doc/system/versions.html#order-of-versions Product
- https://access.redhat.com/errata/RHSA-2026:39809
- https://access.redhat.com/errata/RHSA-2026:54757
- https://access.redhat.com/security/cve/CVE-2026-42790
- https://bugzilla.redhat.com/show_bug.cgi?id=2482286
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42790.json