CVE-2026-57585: MessagePack is the serializer implementation for Python msgpack.org. Prior to 1.2.1, there is an Out-of-bounds read/crash on Unpacker reuse after a caught error, potentially leadin

highCVSS 7.5CVE-2026-57585

MessagePack is the serializer implementation for Python msgpack.org. Prior to 1.2.1, there is an Out-of-bounds read/crash on Unpacker reuse after a caught error, potentially leading to a DoS attack. If the Unpacker is used repeatedly after an error occurs, the process may crash with a SEGV. This issue has been fixed in version 1.2.1.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: high — CVSS 7.5
Published: 2026-06-30
Last updated: 2026-07-02
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-57585

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-575850.28% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 20% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-57585	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

highCVE-2026-57585: MessagePack: Out-of-bounds read/crash on Unpacker reuse after caught errormsrc

Recent advisories for MessagePack is the

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

highCVE-2026-57585: MessagePack: Out-of-bounds read/crash on Unpacker reuse after caught errormsrc · 2026-06-09