Rust OpensslFramework / library · Rust Openssl Project
CVE-2026-41676
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedrust-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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceIn rust-openssl versions 0.9.27 through before 0.10.78, the Deriver::derive and PkeyCtxRef::derive functions pass the caller's buffer length to EVP_PKEY_derive. On OpenSSL 1.1.x, X25519, X448, DH, and HKDF-extract operations ignore the provided length parameter and unconditionally write the full shared secret (32/56/prime-size bytes), causing heap/stack overflow when a shorter buffer is provided.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Rust OpensslFramework / library
>= 0.9.27, < 0.10.78CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check rust-openssl versionInspect your Cargo.lock file for the rust-openssl version entry, or run 'cargo tree -p rust-openssl' to see the installed versionAffected if Version is >= 0.9.27 and < 0.10.78
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Check OpenSSL library versionRun 'openssl version' command, or inspect linked libraries in your compiled binary using 'ldd' on Linux or 'dumpbin' on WindowsAffected if OpenSSL version begins with 1.1.x (for example 1.1.1k). OpenSSL 3.x is NOT affected.
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Identify derive function usageSearch your source code for calls to Deriver::derive() or PkeyCtxRef::derive() methodsAffected if These functions are called in your codebase with buffer slices that may be smaller than the full shared secret size
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Verify key types in useReview which key types your code uses with the derive functions, specifically X25519, X448, DH, or HKDF-extract operationsAffected if Any of these key exchange algorithms are being used with the vulnerable derive functions on OpenSSL 1.1.x
You are affected if you have rust-openssl < 0.10.78, are using OpenSSL 1.1.x, and your code calls Deriver::derive or PkeyCtxRef::derive with buffers shorter than the full key output size.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped0.10.78
Upgrade rust-openssl to version 0.10.78 or later. Ensure any buffer passed to derive functions is sized to accommodate the full expected output (32 bytes for X25519, 56 for X448, prime size for DH).
0.10.78
- Update the rust-openssl dependency in Cargo.toml to version 0.10.78 or later
- Run `cargo update` to fetch the new version
- Run `cargo build` to verify the upgrade compiles successfully
- Run tests to ensure no regressions, particularly any key derivation operations using X25519, X448, DH, or HKDF
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Rust Openssl
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,696.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-41676 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-41676 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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