Heap-based Buffer Overflow Affecting microsoft/SymCrypt package, versions [103.5.0,103.11.0)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Start learning- Snyk IDSNYK-UNMANAGED-MICROSOFTSYMCRYPT-16004870
- published13 Apr 2026
- disclosed6 Apr 2026
- creditFedericoPonzi
Introduced: 6 Apr 2026
CVE-2026-35199 (opens in a new tab)How to fix?
Upgrade microsoft/SymCrypt to version 103.11.0 or higher.
Overview
Affected versions of this package are vulnerable to Heap-based Buffer Overflow in the SymCryptXmssSign function when a 64-bit leaf count value is passed to a helper function that only accepts a 32-bit parameter. This leads to silent truncation, causing an undersized scratch buffer allocation and a subsequent heap buffer overflow during signature computation. An attacker can cause memory corruption and potentially execute arbitrary code by supplying a specially crafted parameter set to trigger the overflow. This is only exploitable if an application allows attacker-controlled parameter sets for XMSS^MT signing operations, which is uncommon as signing typically requires trusted private keys.