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Mbed TlsApplication · Arm

CVE-2026-25835

HIGH · 7.7 CVSS v3.1 Published 2026-04-01
Fix available
A fix is available. Upgrade to 1.1.0 / 3.6.6 or later.
See remediation →
82/100
Remediation priority · High
No privileges Zero-click

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 · unedited
Mbed TLS before 3.6.6 and TF-PSA-Crypto before 1.1.0 misuse seeds in a Pseudo-Random Number Generator (PRNG).

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 confidence

Mbed TLS before version 3.6.6 and TF-PSA-Crypto before version 1.1.0 contain a vulnerability where seeds are misused in the Pseudo-Random Number Generator (PRNG), potentially compromising the randomness of cryptographic operations.

MitigationUpgrade Mbed TLS to version 3.6.6 or later, and TF-PSA-Crypto to version 1.1.0 or later. Validate that the PRNG implementation correctly handles seed generation and storage after the update.

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
Mbed TlsApplication
Affected:>= 2.18.0, < 3.6.6
Mbed TlsApplication
Affected:= 4.0.0
Tf Psa CryptoApplication
Affected:< 1.1.0

CVSS 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
Local
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify which cryptographic library is in use
    Inspect your project dependencies, build system, or binary to determine if Arm Mbed TLS, Trustedfirmware Mbed TLS, or TF-PSA-Crypto is installed. Check headers like mbedtls/version.h, tf/psa/crypto.h, or library filenames.
    Affected if The library is any variant of Mbed TLS or TF-PSA-Crypto
  2. Determine the installed Mbed TLS version
    For Mbed TLS: check the MBEDTLS_VERSION_NUMBER macro in mbedtls/version.h, or run 'grep -r "MBEDTLS_VERSION"' in include/mbedtls/. For build systems: review CMakeLists.txt or package.json for the version tag.
    Affected if Version is >= 2.18.0 and < 3.6.6
  3. Determine the installed TF-PSA-Crypto version
    Check the TF_PSA_CRYPTO_VERSION_NUMBER macro in tf/psa/crypto_version.h, or review the version tag in the Trustedfirmware source checkout.
    Affected if Version is < 1.1.0
  4. Check if the PRNG is being used
    Search source code for calls to mbedtls_ctr_drbg_seed, mbedtls_hmac_drbg_seed, or PSA crypto random generation functions (psa_generate_random, psa_key_derivation). Review initialization code that seeds the PRNG.
    Affected if The PRNG seeding functions are called in the application

You are affected if you use Mbed TLS versions 2.18.0 to < 3.6.6, Mbed TLS 4.0.0, or TF-PSA-Crypto < 1.1.0 and your application initializes the PRNG for cryptographic operations.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Upgrade available Upgrade to 1.1.0 / 3.6.6 or later
Fixed in 1.1.03.6.6
Interim mitigation

Upgrade Mbed TLS to version 3.6.6 or later, and TF-PSA-Crypto to version 1.1.0 or later. Validate that the PRNG implementation correctly handles seed generation and storage after the update.

Recommended fix Moderate confidence

Mbed TLS 3.6.6 or later for 2.x/3.x branches; Mbed TLS 3.6.6 for 4.0.0 users (4.x may be EOL); TF-PSA-Crypto 1.1.0 or later

  1. 1. Identify the current Mbed TLS or TF-PSA-Crypto version in use by checking project dependencies or library files.
  2. 2. For Mbed TLS 2.x and 3.x (versions >= 2.18.0): Upgrade to Mbed TLS version 3.6.6 or later.
  3. 3. For Mbed TLS 4.0.0: Downgrade to Mbed TLS 3.6.6 (the 4.x line may not have a fixed release; check mbed-tls.readthedocs.io for latest guidance).
  4. 4. For TF-PSA-Crypto: Upgrade to version 1.1.0 or later.
  5. 5. Rebuild and redeploy the application with the updated library.
  6. 6. Verify the PRNG implementation now correctly handles seeds according to current best practices.
Caveat Downgrading from Mbed TLS 4.0.0 to 3.6.6 may introduce API/ABI differences; verify compatibility with existing application code

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Mbed Tls Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing12.0 h
  • Review / QA6.0 h
26.0 hours of engineering $4,400
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-25835 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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  • No spam, self-promotion, credentials, or personal data