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CVE-2026-35199
MEDIUM · CVSS 6.1
EPSS exploitation probability: 0%
Published 2026-04-06T20:16:27.543 · Last modified 2026-06-17T10:40:11.850

Summary

SymCrypt is the core cryptographic function library currently used by Windows. From 103.5.0 to before 103.11.0, The SymCryptXmssSign function passes a 64-bit leaf count value to a helper function that accepts a 32-bit parameter. For XMSS^MT parameter sets with total tree height >= 32 (which includes standard predefined parameters), this causes silent truncation to zero, resulting in a drastically undersized scratch buffer allocation followed by a heap buffer overflow during signature computation. Exploiting this issue would require an application using SymCrypt to perform an XMSS^MT signature using an attacker-controlled parameter set. It is uncommon for applications to allow the use of attacker-controlled parameter sets for signing, since signing is a private key operation, and private ke

Affected products

microsoft — symcrypt

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.