Vulnerability · Published May 14, 2026 · Assigned by GitHub_M

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

High 7.5

In plain English

A high-severity security flaw in Nerdbank.MessagePack from AArnott. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 29% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.4%top 70.8% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Nerdbank.MessagePack is a NativeAOT-compatible MessagePack serialization library. Prior to 1.1.62, 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. This vulnerability is fixed in 1.1.62.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
NuGet	nerdbank.messagepack	1.1.62	GHSA-2cwq-pwfr-wcw3

Affected products (as reported)

Vendor	Product	Versions
AArnott	Nerdbank.MessagePack	< 1.1.62

Weakness: CWE-789 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

https://github.com/AArnott/Nerdbank.MessagePack/security/advisories/GHSA-2cwq-pwfr-wcw3 x_refsource_CONFIRM
https://github.com/AArnott/Nerdbank.MessagePack/pull/941 x_refsource_MISC
https://github.com/AArnott/Nerdbank.MessagePack/commit/7d1eb319cfabe7280e70699946c9a48579fa2f30 x_refsource_MISC
https://github.com/AArnott/Nerdbank.MessagePack/releases/tag/v1.1.62 x_refsource_MISC