Ingela Andin

**Name of the Vulnerable Software and Affected Versions** Erlang OTP versions 17.0 through 26.2.5.20 Erlang OTP versions 27.x prior to 27.3.4.12 Erlang OTP versions 28.x prior to 28.5.0.1 Erlang OTP versions 29.x prior to 29.0.1 public key versions 0.22 through 1.15.1.6 public key versions 1.17.x prior to 1.17.1.3 public key versions 1.20.x prior to 1.20.3.1 public key versions 1.21.x prior to 1.21.1 **Description** Improper following of a certificate's chain of trust in the `pubkey cert` module allows a non-CA certificate to be accepted as an intermediate issuer, enabling certificate chain forgery. The function `pubkey cert:validate extensions/7` contains flaws where a certificate with `basicConstraints` set to `cA:false` and no `keyUsage` extension can be used as an intermediate issuer in a chain passed to `public key:pkix path validation/3`. This occurs because the `cA:false` clause does not reject the certificate when it is in the issuer position, and the `keyUsage` check is bypassed if the extension is entirely absent. Consequently, an attacker with an end-entity certificate issued by a trusted CA can sign forged leaf certificates for arbitrary identities. This affects all TLS or mTLS endpoints built on the OTP ssl application using the default verifier, including client-side server identity verification and mTLS server client certificate verification. **Recommendations** Update Erlang OTP to version 26.2.5.21, 27.3.4.12, 28.5.0.1, or 29.0.1 depending on the current release branch. Update public key to version 1.15.1.7, 1.17.1.3, 1.20.3.1, or 1.21.1 depending on the current release branch. Use the `verify fun` option in the ssl or public key application to ensure path validation rejects chains where an intermediate certificate lacks `basicConstraints cA:true`.

**Name of the Vulnerable Software and Affected Versions** Erlang OTP versions 27.0 through 27.3.4.11 Erlang OTP versions prior to 28.5.0.1 Erlang OTP versions prior to 29.0.1 public key versions 1.16 through 1.17.1.2 public key versions prior to 1.20.3.1 public key versions prior to 1.21.1 **Description** Improper Certificate Validation in the `pubkey ocsp` module of Erlang OTP `public key` allows forged Online Certificate Status Protocol (OCSP) responses signed with an expired responder certificate to be accepted as valid. The functions `verify response/5` and `is authorized responder/3` fail to check the validity period (`notBefore`/`notAfter`) of the OCSP responder certificate. An attacker possessing the private key of an expired CA-designated OCSP responder certificate can forge responses that the system accepts. This impacts TLS clients using OCSP stapling via the `ssl` application, potentially allowing a compromised server to present a revoked TLS certificate as valid. It also affects applications directly calling the `pkix ocsp validate/5` function, which may lead to authentication bypass during server-side client certificate validation. **Recommendations** Update Erlang OTP to version 27.3.4.12, 28.5.0.1, or 29.0.1. Update public key to version 1.17.1.3, 1.20.3.1, or 1.21.1. For TLS clients using the `ssl` application, disable OCSP stapling by setting `{stapling, no staple}` in client options or switch to CRL-based revocation checking with `{crl check, true}`. For applications calling `pkix ocsp validate/5` directly, validate the responder certificate's validity period in the application code before calling the function.

**Name of the Vulnerable Software and Affected Versions** Erlang OTP versions 17.0 through 28.0.3 Erlang OTP versions 26.2.5.15 through 27.3.4.3 Erlang OTP versions 27.3.4.3 Erlang OTP versions 28.0.3 ssh versions 3.0.1 through 5.3.3 ssh versions 5.1.4.12 ssh versions 5.2.11.3 **Description** An Allocation of Resources Without Limits or Throttling issue exists in Erlang OTP ssh (ssh sftp modules), potentially leading to Excessive Allocation and Resource Leak Exposure. The issue is associated with the `ssh sftpd.erl` file. **Recommendations** Update Erlang OTP to a version later than 28.0.3. Update ssh to a version later than 5.3.3. Update ssh to a version later than 5.2.11.3. Update ssh to a version later than 5.1.4.12.

**Name of the Vulnerable Software and Affected Versions** Erlang OTP versions 17.0 through 28.0.3 Erlang OTP versions 26.2.5.15 through 27.3.4.3 Erlang OTP versions 27.3.4.3 Erlang OTP versions 28.0.3 ssh versions 3.0.1 through 5.3.3 ssh versions 5.1.4.12 ssh versions 5.2.11.3 **Description** An Allocation of Resources Without Limits or Throttling issue exists in Erlang OTP ssh (ssh sftp modules), potentially leading to Excessive Allocation and Resource Leak Exposure. The issue is associated with the `ssh sftpd.erl` file. **Recommendations** Update Erlang OTP to a version later than 28.0.3. Update ssh to a version later than 5.3.3. Update ssh to a version later than 5.2.11.3. Update ssh to a version later than 5.1.4.12.

**Name of the Vulnerable Software and Affected Versions** Erlang OTP versions 17.0 through 28.0.3 Erlang OTP versions 26.2.5.15 Erlang OTP versions 27.3.4.3 ssh versions 3.0.1 through 5.3.3 ssh versions 5.1.4.12 ssh versions 5.2.11.3 **Description** An uncontrolled resource consumption issue exists in Erlang OTP ssh (ssh sftp modules), allowing excessive allocation and flooding. The issue is associated with the `ssh sftpd.erl` file. **Recommendations** Update Erlang OTP to a version later than 28.0.3. Update ssh to a version later than 5.3.3. Update ssh to a version later than 5.2.11.3. Update ssh to a version later than 5.1.4.12.

**Name of the Vulnerable Software and Affected Versions** Erlang OTP versions 17.0 through 28.0.3 Erlang OTP versions 26.2.5.15 Erlang OTP versions 27.3.4.3 **Description** An Allocation of Resources Without Limits or Throttling issue exists in the Erlang OTP ssh (ssh sftp modules), potentially leading to Excessive Allocation and Flooding. The vulnerability is associated with the `ssh sftpd.erl` file. **Recommendations** Update Erlang OTP to a version later than 28.0.3. Update Erlang OTP to a version later than 26.2.5.15. Update Erlang OTP to a version later than 27.3.4.3.