Out-of-bounds Read Vulnerability in Python MessagePack Implementation
CVE-2026-57585

7.5HIGH

Key Information:

Vendor

Msgpack

Status
Msgpack-python
Vendor
CVE Published:
30 June 2026

What is CVE-2026-57585?

The MessagePack serializer implementation for Python contains a vulnerability that may allow for an out-of-bounds read and potential Denial of Service (DoS) when the Unpacker is reused after catching an error. Specifically, when the Unpacker is called multiple times following an error, the repeated invocation can cause the process to crash due to a segmentation fault (SEGV). This flaw has been resolved in version 1.2.1, urging users to update promptly to mitigate the risks associated with this issue.

Affected Version(s)

msgpack-python < 1.2.1

References

https://github.com/msgpack/msgpack-python/security/adviso...
x_refsource_CONFIRM
https://github.com/msgpack/msgpack-python/commit/2c56ddb5...
x_refsource_MISC

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.