OpenSSL have published a security advisory. Here's how it affects BoringSSL:
| CVE | Summary | Severity in OpenSSL | Impact to BoringSSL |
|---|---|---|---|
| CVE-2023-0464 | Excessive Resource Usage Verifying X.509 Policy Constraints | Low | Fixed January 2023 |
We discovered this bug while working on the X.509 code in BoringSSL and Chromium. It is discussed in detail in this IETF draft we published (latest snapshot as of writing). Rather than capping the nodes, BoringSSL implements the draft's more efficient DAG strategy. Callers that enable X.509 policy validation should update to commit ba68ca070ca939 (January 20, 2023) or later.
Policy checking is enabled if one of the following APIs is used:
X509_VERIFY_PARAM_set1_policiesX509_V_FLAG_POLICY_CHECKX509_V_FLAG_EXPLICIT_POLICYX509_V_FLAG_INHIBIT_ANYX509_V_FLAG_INHIBIT_MAPFuture revisions of BoringSSL may enable it unconditionally to address some issues with critical extensions, but only with the new, efficient implementation.
January 27th, 2026 addendum: Policy validation was enabled unconditionally in BoringSSL shortly after this advisory was published, on March 30th, 2023. Our improved policy validation algorithm was published as RFC 9618.