DEBIAN-CVE-2026-42790

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Source
https://security-tracker.debian.org/tracker/CVE-2026-42790
Import Source
https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-42790.json
JSON Data
https://api.osv.dev/v1/vulns/DEBIAN-CVE-2026-42790
Upstream
Published
2026-05-27T17:16:36Z
Modified
2026-09-19T22:47:35Z
Severity
  • 8.1 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N CVSS Calculator
Summary
[none]
Details

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.

References

Affected packages

Debian:12 / erlang

Package

Name
erlang
Purl
pkg:deb/debian/erlang?arch=source&distro=bookworm

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1:25.*
1:25.2.3+dfsg-1
1:25.2.3+dfsg-1+deb12u1
1:25.2.3+dfsg-1+deb12u2
1:25.2.3+dfsg-1+deb12u3
1:25.2.3+dfsg-1+deb12u4
1:25.3.2.8+dfsg-1
1:25.3.2.10+dfsg-1
1:25.3.2.10+dfsg-2
1:25.3.2.11+dfsg-1
1:25.3.2.12+dfsg-1
1:25.3.2.12+dfsg-2
1:25.3.2.12+dfsg-3
1:26.*
1:26.0~rc2+dfsg-1
1:26.0~rc3+dfsg-1
1:26.0+dfsg-1
1:26.0.1+dfsg-1
1:26.0.2+dfsg-1
1:26.1.2+dfsg-1
1:26.2.1+dfsg-1
1:26.2.4+dfsg-1
1:27.*
1:27.0~rc3+dfsg-1
1:27.0~rc3+dfsg-2
1:27.0~rc3+dfsg-3
1:27.0~rc3+dfsg-4
1:27.0+dfsg-1
1:27.0.1+dfsg-1
1:27.0.1+dfsg-2
1:27.0.1+dfsg-3
1:27.1.2+dfsg-1
1:27.2+dfsg-1
1:27.2+dfsg-2
1:27.2+dfsg-3~exp1
1:27.2.1+dfsg-1
1:27.2.1+dfsg-2
1:27.2.2+dfsg-1
1:27.2.3+dfsg-1
1:27.2.4+dfsg-1
1:27.3+dfsg-1
1:27.3.1+dfsg-1
1:27.3.2+dfsg-1
1:27.3.3+dfsg-1
1:27.3.4+dfsg-1
1:27.3.4.1+dfsg-1
1:27.3.4.3+dfsg-1
1:27.3.4.4+dfsg-1
1:27.3.4.6+dfsg-1
1:27.3.4.8+dfsg-1
1:27.3.4.9+dfsg-1
1:27.3.4.10+dfsg-1
1:27.3.4.11+dfsg-1
1:27.3.4.11+dfsg-2
1:27.3.4.11+dfsg-3
1:27.3.4.11+dfsg-4
1:27.3.4.11+dfsg-5
1:27.3.4.11+dfsg-6
1:27.3.4.11+dfsg-7
1:27.3.4.12+dfsg-1
1:28.*
1:28.0+dfsg-1
1:28.0.1+dfsg-1
1:28.0.2+dfsg-1
1:28.0.4+dfsg-1
1:28.1.1+dfsg-1
1:28.2+dfsg-1
1:28.3+dfsg-1
1:28.3.1+dfsg-1
1:29.*
1:29.0~rc1+dfsg-1
1:29.0~rc1+dfsg-2
1:29.0~rc2+dfsg-1
1:29.0~rc3+dfsg-1
1:29.0~rc3+dfsg-2
1:29.0~rc3+dfsg-3
1:29.0~rc3+dfsg-4
1:29.0+dfsg-1
1:29.0+dfsg-2
1:29.0.1+dfsg-1
1:29.0.2+dfsg-1
1:29.0.3+dfsg-1
1:29.0.4+dfsg-1
1:29.0.6+dfsg-1

Ecosystem specific 

{
    "urgency": "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-42790.json"

Debian:13 / erlang

Package

Name
erlang
Purl
pkg:deb/debian/erlang?arch=source&distro=trixie

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
1:27.3.4.1+dfsg-1+deb13u3

Affected versions

1:27.*
1:27.3.4.1+dfsg-1
1:27.3.4.1+dfsg-1+deb13u1
1:27.3.4.1+dfsg-1+deb13u2

Ecosystem specific 

{
    "urgency": "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-42790.json"

Debian:14 / erlang

Package

Name
erlang
Purl
pkg:deb/debian/erlang?arch=source&distro=forky

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
1:27.3.4.12+dfsg-1

Affected versions

1:27.*
1:27.3.4.1+dfsg-1
1:27.3.4.3+dfsg-1
1:27.3.4.4+dfsg-1
1:27.3.4.6+dfsg-1
1:27.3.4.8+dfsg-1
1:27.3.4.9+dfsg-1
1:27.3.4.10+dfsg-1
1:27.3.4.11+dfsg-1
1:27.3.4.11+dfsg-2
1:27.3.4.11+dfsg-3
1:27.3.4.11+dfsg-4
1:27.3.4.11+dfsg-5
1:27.3.4.11+dfsg-6
1:27.3.4.11+dfsg-7

Ecosystem specific 

{
    "urgency": "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-42790.json"