CVE-2026-42789
Description
A flaw was found in Erlang OTP's public_key module. This vulnerability (CWE-295), related to improper certificate validation, allows a non-Certificate Authority (CA) certificate to be accepted as an intermediate issuer. A remote attacker, holding an end-entity certificate issued by a trusted CA, can exploit this by forging leaf certificates for arbitrary identities. This can lead to compromised server identity verification on the client side and client certificate verification on mutual Transport Layer Security (mTLS) servers, undermining the trust in certificate-based authentication.
Statement
This is an Important vulnerability where Erlang OTP's public_key module improperly validates certificate chains. A remote attacker with an existing end-entity certificate from a trusted Certificate Authority can forge new leaf certificates, leading to compromised server or client identity verification in TLS/mTLS connections. This impacts applications within Red Hat OpenStack Platform and Community Projects that utilize the default verifier in the OTP ssl application. Because an attacker must be able to create or locate a certificate with specific attributes, Red Hat assesses the impact of this vulnerability as Important.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8 | 4.8 | 8 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | High | High | High |
| Privileges Required | None | None | None |
| User Interaction | Required | None | Required |
| Scope | Changed | Unchanged | Changed |
| Confidentiality | High | Low | High |
| Integrity Impact | High | Low | High |
| Availability Impact | None | None | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N
NVD: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N
Understanding the Weakness (CWE)
Integrity,Authentication
Technical Impact: Bypass Protection Mechanism; Gain Privileges or Assume Identity
When a certificate is invalid or malicious, it might allow an attacker to spoof a trusted entity by interfering in the communication path between the host and client. The product might connect to a malicious host while believing it is a trusted host, or the product might be deceived into accepting spoofed data that appears to originate from a trusted host.
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