CVE-2026-41676
rust-openssl: Deriver::derive and PkeyCtxRef::derive can overflow short buffers on OpenSSL 1.1.1
Description
rust-openssl provides OpenSSL bindings for the Rust programming language. From 0.9.27 to before 0.10.78, Deriver::derive (and PkeyCtxRef::derive) sets len = buf.len() and passes it as the in/out length to EVP_PKEY_derive, relying on OpenSSL to honor it. On OpenSSL 1.1.x, X25519, X448, DH and HKDF-extract ignore the incoming *keylen, unconditionally writing the full shared secret (32/56/prime-size bytes). A caller passing a short slice gets a heap/stack overflow from safe code. OpenSSL 3.x providers do check, so this only impacts older OpenSSL. This vulnerability is fixed in 0.10.78.
How to fix CVE-2026-41676
To remediate CVE-2026-41676, upgrade the affected package to a fixed version below.
- —upgrade to 0.10.78 or later
- —no fix listed
Is CVE-2026-41676 being exploited?
Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.
Affected packages (2)
- >= 0.9.27, < 0.10.78
- from 0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U |
| osv | CVSS 3.1 | CRITICAL9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |