Executive brief
rust-openssl is a library that allows Rust applications to use OpenSSL for secure communications and cryptography. A flaw in how it handles certain cryptographic operations when using older versions of OpenSSL (1.1.x) can cause a program to crash or behave unpredictably. This occurs when the library fails to properly limit the amount of data written to memory during key derivation, potentially leading to service instability.
Technical details
A buffer overflow vulnerability exists in rust-openssl's Deriver::derive and PkeyCtxRef::derive functions. The root cause is an incorrect assumption that OpenSSL's EVP_PKEY_derive honors the provided buffer length. On OpenSSL 1.1.x, specific algorithms (X25519, X448, DH, and HKDF-extract) ignore the input length and unconditionally write the full shared secret. If a caller provides a buffer smaller than the secret size, an out-of-bounds write occurs on the heap or stack. This issue specifically affects environments using OpenSSL 1.1.x; OpenSSL 3.x providers include the necessary checks. The vulnerability is addressed in version 0.10.78.
Affected products
- rust-openssl project rust-openssl >= 0.9.27, < 0.10.78
Timeline
- 2026-04-19: advisory: GitHub advisory GHSA-pqf5-4pqq-29f5 published
- 2026-04-24: disclosed: CVE-2026-41676 published to NVD