CVE-2026-34875
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 · uneditedAn issue was discovered in Mbed TLS through 3.6.5 and TF-PSA-Crypto 1.0.0. A buffer overflow can occur in public key export for FFDH keys.
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 · moderate confidenceA buffer overflow vulnerability exists in Mbed TLS through 3.6.5 and TF-PSA-Crypto 1.0.0 in the public key export functionality for FFDH (Finite Field Diffie-Hellman) keys. The vulnerability allows overflowing buffers during key serialization, potentially enabling remote code execution or denial of service with CRITICAL severity (CVSS 9.8).
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>= 3.5.0, < 3.6.6< 1.1.0CVSS 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
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 Mbed TLS library versionInspect the library binary or version header file (e.g., mbedtls/version.h) or use mbedtls_version_get_number() API callAffected if Installed version is >= 3.5.0 and < 3.6.6
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Check TF-PSA-Crypto library versionInspect the TF-PSA-Crypto library binary or version header file, or query the PSA crypto version at runtimeAffected if Installed version is < 1.1.0
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Verify FFDH key export is in useSearch application code or configuration for calls to key export functions such as mbedtls_pk_export, mbedtls_pk_export_key, or PSA key export APIs involving MBEDTLS_PK_DH or PSA_KEY_TYPE_DH keysAffected if FFDH (Diffie-Hellman) public or private key export functions are invoked in the application
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Check for large FFDH key sizesReview the application key generation or import process to determine if FFDH keys with large prime sizes (e.g., 2048-bit or higher) are being serializedAffected if FFDH keys with large prime field parameters are exported using vulnerable serialization code
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Identify export buffer allocationAudit memory allocation calls preceding FFDH key export operations; check if buffers are sized based on estimated maximum rather than exact computed requirementsAffected if Export buffers are statically sized without accounting for overflow conditions in the vulnerable serialization path
The environment is affected if it runs any version of Mbed TLS 3.5.0 through 3.6.5 or TF-PSA-Crypto versions prior to 1.1.0 AND uses FFDH key export functionality, allowing buffer overflow during key serialization.
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 · scoped1.1.03.6.6
Upgrade to Mbed TLS version 3.6.6 or later, or TF-PSA-Crypto 1.0.1 or later, which contain the fix for this buffer overflow vulnerability. If upgrades are not immediately possible, disable or restrict FFDH key export functionality as a temporary workaround.
Mbed TLS 3.6.6 and TF-PSA Crypto 1.1.0
- 1. Identify all applications and systems using Mbed TLS libraries in the version range >=3.5.0 and <3.6.6
- 2. Identify all applications and systems using TF-PSA Crypto versions <1.1.0
- 3. Obtain the fixed releases: Mbed TLS 3.6.6 and TF-PSA Crypto 1.1.0 from the official mbed-tls repository or distribution channels
- 4. Replace the affected library binaries or source code with the fixed versions
- 5. Recompile and rebuild any applications statically linked to the affected libraries
- 6. Test the updated systems to verify that FFDH key export functionality works correctly
- 7. Deploy the updated libraries to all production systems
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation8.0 h
- Testing12.0 h
- Review / QA6.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-34875 — 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-2026-34875 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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