Impact

Due to a non-constant-time implementation, information about the private key is leaked through timing information which is observable over the network. An attacker may be able to use that information to recover the key.

Patches

No patch is yet available. The crypto-bigint migration (RustCrypto/RSA#394) did not close this. Tracking is RustCrypto/RSA#626 (padding still not constant-time). Implicit rejection work is in RustCrypto/RSA#680; default-path blinding is in RustCrypto/RSA#702.

Still affected as of 2026-09-12: rsa 0.9.10 (latest stable) and rsa 0.10.0-rc.18 (latest). patched = [] is intentional.

Workarounds

Avoid using the rsa crate in settings where attackers can observe timing, for example over the network. Local use on a non-compromised computer is fine.

References

This vulnerability was discovered as part of the "Marvin Attack", which revealed several implementations of RSA including OpenSSL had not properly mitigated timing sidechannel attacks.

ring::aead::quic::HeaderProtectionKey::new_mask() may panic when overflow checking is enabled. In the QUIC protocol, an attacker can induce this panic by sending a specially-crafted packet. Even unintentionally it is likely to occur in 1 out of every 2**32 packets sent and/or received.

On 64-bit targets operations using ring::aead::{AES_128_GCM, AES_256_GCM} may panic when overflow checking is enabled, when encrypting/decrypting approximately 68,719,476,700 bytes (about 64 gigabytes) of data in a single chunk. Protocols like TLS and SSH are not affected by this because those protocols break large amounts of data into small chunks. Similarly, most applications will not attempt to encrypt/decrypt 64GB of data in one chunk.

Overflow checking is not enabled in release mode by default, but RUSTFLAGS="-C overflow-checks" or overflow-checks = true in the Cargo.toml profile can override this. Overflow checking is usually enabled by default in debug mode.

Name constraints for URI names were ignored and therefore accepted.

Note this library does not provide an API for asserting URI names, and URI name constraints are otherwise not implemented. URI name constraints are now rejected unconditionally.

Since name constraints are restrictions on otherwise properly-issued certificates, this bug is reachable only after signature verification and requires misissuance to exploit.

This vulnerability is identified as GHSA-965h-392x-2mh5. Thank you to @1seal for the report.

Permitted subtree name constraints for DNS names were accepted for certificates asserting a wildcard name.

This was incorrect because, given a name constraint of accept.example.com, *.example.com could feasibly allow a name of reject.example.com which is outside the constraint. This is very similar to CVE-2025-61727.

Since name constraints are restrictions on otherwise properly-issued certificates, this bug is reachable only after signature verification and requires misissuance to exploit.

This vulnerability is identified as GHSA-xgp8-3hg3-c2mh. Thank you to @1seal for the report.

A panic was reachable when parsing certificate revocation lists via [BorrowedCertRevocationList::from_der] or [OwnedCertRevocationList::from_der]. This was the result of mishandling a syntactically valid empty BIT STRING appearing in the onlySomeReasons element of a IssuingDistributionPoint CRL extension.

This panic is reachable prior to a CRL's signature being verified.

Applications that do not use CRLs are not affected.

Thank you to @tynus3 for the report.