Nerdbank.MessagePack: Attacker-controlled stackalloc in DateTime decoding causes process-terminating StackOverflowException — CVE-2026-44375

Summary

### Summary Nerdbank.MessagePack contains an uncontrolled stack allocation vulnerability in DateTime decoding. A malicious MessagePack payload can declare an oversized timestamp extension length, causing the reader to allocate an attacker-controlled number of bytes on the stack. This can trigger a `StackOverflowException`, which is not catchable by user code and terminates the process. ### Impact Applications are…

Product

nuget: Nerdbank.MessagePack

What to do

General, cautious steps (verify details in the official source):

• Prioritize patching or mitigation immediately (treat as actively risky).
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

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