REDHAT-BUG-2482093: High severity Ericsson Erlang OTP vulnerability
Improper Following of a Certificate's Chain of Trust vulnerability in Erlang OTP publickey (pubkeycert module) allows a non-CA certificate to be accepted as an intermediate issuer, enabling certificate chain forgery.
In lib/publickey/src/pubkeycert.erl, pubkeycert:validateextensions/7 contains two flaws that together allow a certificate with basicConstraints cA:false and no keyUsage extension to be used as an intermediate issuer in a chain passed to publickey:pkixpathvalidation/3: the cA:false clause recurses into the remaining extensions without rejecting the certificate when it is in issuer position, and the keyUsage check only fires when the extension is present, so a certificate lacking keyUsage entirely bypasses the keyCertSign enforcement.
Any party holding an end-entity certificate with basicConstraints cA:false and no keyUsage extension, issued by any CA in the victim's trust store, can use that certificate's private key to sign forged leaf certificates for arbitrary identities. publickey:pkixpathvalidation/3 accepts the resulting chain, and by extension every TLS or mTLS endpoint built on the OTP ssl application that relies on the default verifier is affected, including server identity verification on the client side and client certificate verification on mTLS servers.
This issue affects OTP from OTP 17.0 before OTP 26.2.5.21, 27.3.4.12, 28.5.0.1, and 29.0.1 corresponding to publickey from 0.22 before 1.15.1.7, 1.17.1.3, 1.20.3.1, and 1.21.1.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Erlang OTP (public_key application / pubkey_cert)to a version that resolves this vulnerability.Fixed in OTP 26.2.5.21 - Upgrade
Upgrade
Erlang public_key (lib/public_key/src/pubkey_cert.erl)to a version that resolves this vulnerability.Fixed in 1.15.1.7 - Upgrade
Upgrade
Erlang public_key (lib/public_key/src/pubkey_cert.erl)to a version that resolves this vulnerability.Fixed in 1.17.1.3 - Upgrade
Upgrade
Erlang public_key (lib/public_key/src/pubkey_cert.erl)to a version that resolves this vulnerability.Fixed in 1.20.3.1 - Upgrade
Upgrade
Erlang public_key (lib/public_key/src/pubkey_cert.erl)to a version that resolves this vulnerability.Fixed in 1.21.1 - Configuration
Ensure TLS/mTLS endpoints using OTP ssl with the default verifier run on Erlang OTP/public_key versions at or after the listed fixed versions.
OTP ssl application (default certificate verifier) Certificate verification behavior via default verifier = Update to a fixed Erlang OTP/public_key version so pubkey_cert:validate_extensions/7 enforces correct intermediate-issuer rules (reject non-CA certificates with basicConstraints cA:false and enforce keyUsage keyCertSign).
Event History
Frequently Asked Questions
What is the severity of REDHAT-BUG-2482093?
The severity of REDHAT-BUG-2482093 is classified as high with a score of 7.
How do I fix REDHAT-BUG-2482093?
To fix REDHAT-BUG-2482093, update your Ericsson Erlang OTP public_key module to the latest patched version.
What type of vulnerability is REDHAT-BUG-2482093?
REDHAT-BUG-2482093 is an improper following of a certificate's chain of trust vulnerability.
What software is affected by REDHAT-BUG-2482093?
The affected software for REDHAT-BUG-2482093 is the Ericsson Erlang OTP, specifically the public_key module.
What are the potential consequences of REDHAT-BUG-2482093?
The potential consequences of REDHAT-BUG-2482093 include the risk of certificate chain forgery, which could lead to unauthorized access or data breaches.