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Untriaged
Permalink CVE-2026-42790
7.6 HIGH
  • CVSS version (CVSS): 4.0
  • Attack Vector (AV): Network (N)
  • Attack Complexity (AC): High (H)
  • Attack Requirement (AT): Present (P)
  • Privileges Required (PR): None (N)
  • User Interaction (UI): Passive (P)
  • Vulnerable System Impact Confidentiality (VC): High (H)
  • Vulnerable System Impact Integrity (VI): High (H)
  • Vulnerable System Impact Availability (VA): None (N)
  • Subsequent System Impact Confidentiality (SC): None (N)
  • Subsequent System Impact Integrity (SI): None (N)
  • Subsequent System Impact Availability (SA): None (N)
  • Modified Attack Vector (MAV): Network (N)
  • Modified Attack Complexity (MAC): High (H)
  • Modified Attack Requirement (MAT): Present (P)
  • Modified Privileges Required (MPR): None (N)
  • Modified User Interaction (MUI): Passive (P)
  • Modified Vulnerable System Impact Confidentiality (MVC): High (H)
  • Modified Vulnerable System Impact Integrity (MVI): High (H)
  • Modified Vulnerable System Impact Availability (MVA): None (N)
  • Modified Subsequent System Impact Confidentiality (MSC): Negligible (N)
  • Modified Subsequent System Impact Integrity (MSI): Negligible (N)
  • Modified Subsequent System Impact Availability (MSA): Negligible (N)
  • Safety (S): Not Defined (X)
  • Automatable (AU): Not Defined (X)
  • Recovery (R): Not Defined (X)
  • Value Density (V): Not Defined (X)
  • Vulnerability Response Effort (RE): Not Defined (X)
  • Provider Urgency (U): Not Defined (X)
  • Confidentiality Req. (CR): Not Defined (X)
  • Integrity Req. (IR): Not Defined (X)
  • Availability Req. (AR): Not Defined (X)
  • Exploit Maturity (E): Not Defined (X)
created 4 weeks ago Activity log
  • Created suggestion 4 weeks ago
nameConstraints DNS bypass via subject CommonName fallback in public_key hostname verification

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.

Affected products

erlang/otp
  • *
public_key
  • *

Matching in nixpkgs

pkgs.cotp

Trustworthy, encrypted, command-line TOTP/HOTP authenticator app with import functionality

pkgs.otpw

One-time password login package

  • nixos-unstable 1.5
    • nixpkgs-unstable 1.5
    • nixos-unstable-small 1.5

pkgs.libcotp

C library that generates TOTP and HOTP

pkgs.otpauth

Google Authenticator migration decoder

pkgs.hotpatch

Hot patching executables on Linux using .so file injection

  • nixos-unstable 0.2
    • nixpkgs-unstable 0.2
    • nixos-unstable-small 0.2

pkgs.totp-cli

Authy/Google Authenticator like TOTP CLI tool written in Go

pkgs.otpclient

Highly secure and easy to use OTP client written in C/GTK that supports both TOTP and HOTP

pkgs.tpm2-totp

Attest the trustworthiness of a device against a human using time-based one-time passwords

pkgs.godotpcktool

Standalone tool for extracting and creating Godot .pck files

  • nixos-unstable 2.2
    • nixpkgs-unstable 2.2
    • nixos-unstable-small 2.2

pkgs.nitrotpm-tools

Collection of utilities for working with NitroTPM attestation

pkgs.gnomeExtensions.totp

Generate One-Time Passwords (aka OTP, both TOTP and HOTP) for websites that use Two-Factor Authentication (2FA) like Google, Facebook, Discord, Amazon, Steam, etc.

  • nixos-unstable 54
    • nixpkgs-unstable 54
    • nixos-unstable-small 54

pkgs.tpm2-totp-with-plymouth

Attest the trustworthiness of a device against a human using time-based one-time passwords

pkgs.gnomeExtensions.bootpaper

Randomly selects a new wallpaper on startup from local folder

  • nixos-unstable 6
    • nixpkgs-unstable 6
    • nixos-unstable-small 6

Package maintainers