CVE-2026-41676 — openssl
Fix: rust-openssl/rust-openssl#2606CVE-2026-41676 is a CWE-131 vulnerability in openssl. A fix is available for openssl — see the affected versions and patch details below.
rust-openssl: Deriver::derive and PkeyCtxRef::derive can overflow short buffers on OpenSSL 1.1.1
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-41676.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
opensslReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | openssl | ≥ 0.9.27&&< 0.10.78 | 0.10.78cargo update -p openssl --precise 0.10.78 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for openssl, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update openssl to 0.10.78 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-41676 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-41676 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-41676. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-41676 in your dependencies?
O3 Security finds CVE-2026-41676 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.