CVE-2023-6935
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 · uneditedwolfSSL SP Math All RSA implementation is vulnerable to the Marvin Attack, new variation of a timing Bleichenbacher style attack, when built with the following options to configure: --enable-all CFLAGS="-DWOLFSSL_STATIC_RSA" The define “WOLFSSL_STATIC_RSA” enables static RSA cipher suites, which is not recommended, and has been disabled by default since wolfSSL 3.6.6. Therefore the default build since 3.6.6, even with "--enable-all", is not vulnerable to the Marvin Attack. The vulnerability is specific to static RSA cipher suites, and expected to be padding-independent. The vulnerability allows an attacker to decrypt ciphertexts and forge signatures after probing with a large number of test observations. However the server’s private key is not exposed.
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 confidencewolfSSL's RSA implementation with WOLFSSL_STATIC_RSA enabled is vulnerable to the Marvin Attack, a timing side-channel variant of Bleichenbacher's attack. This allows attackers to decrypt ciphertexts and forge signatures through many timing observations, but does not expose the private key.
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>= 3.12.2, <= 5.6.4CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
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 wolfSSL versionRun 'wolfssl version' or inspect the library binary with 'strings' and search for version string patterns like 'wolfSSL 5.6.4' or use the API function wolfSSL_Version()Affected if The installed version is between 3.12.2 and 5.6.4 inclusive
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Verify WOLFSSL_STATIC_RSA build flag is enabledSearch the build configuration files (configure.ac, Makefile, or build output) for 'WOLFSSL_STATIC_RSA' or inspect compiled objects with 'grep -r WOLFSSL_STATIC_RSA' in the source tree or binaryAffected if WOLFSSL_STATIC_RSA is defined in the build configuration
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Confirm RSA is in useReview application configuration for RSA cipher suites (such as TLS_RSA_*) in wolfSSL settings, or check if RSA key exchange or RSA signatures are enabled in the wolfSSL build optionsAffected if RSA key exchange or RSA signatures are enabled in the wolfSSL configuration
A user is affected if their wolfSSL version falls within 3.12.2 to 5.6.4 AND the WOLFSSL_STATIC_RSA flag is enabled in the build AND they are using RSA for encryption/decryption or signatures.
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 · scopedRemove the WOLFSSL_STATIC_RSA build flag or upgrade to wolfSSL 3.6.6+ where static RSA is disabled by default.
wolfSSL 5.6.6 or later (if upgrade is desired for additional security improvements)
- Do not build wolfSSL with the --enable-all CFLAGS="-DWOLFSSL_STATIC_RSA" configuration option
- If static RSA is currently enabled, rebuild wolfSSL without the WOLFSSL_STATIC_RSA define
- Ensure the default configuration is used (static RSA has been disabled by default since wolfSSL 3.6.6)
- After rebuilding, verify that static RSA cipher suites are not enabled by checking that WOLFSSL_STATIC_RSA is not defined in the build configuration
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-6935 — 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-2023-6935 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
- No weaponised exploit code, or anything meant to cause harm
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