GHSA-6v7p-g79w-8964

Suggest an improvement
Source
https://github.com/advisories/GHSA-6v7p-g79w-8964
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-6v7p-g79w-8964/GHSA-6v7p-g79w-8964.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-6v7p-g79w-8964
Aliases
Downstream
CGA (255)
ECHO (1)
MINI (18)
ROOT (1)
Published
2026-06-19T21:42:55Z
Modified
2026-09-10T03:51:07Z
Severity
  • 7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
Summary
MessagePack for Python: Out-of-bounds read / crash on Unpacker reuse after a caught error
Details

Impact

If the Unpacker is used repeatedly after an error occurs, the process may crash with a SEGV.

If the Unpacker is used repeatedly to unpack untrusted input from external sources, it may be vulnerable to a DoS attack.

Patches

v1.2.1

Workarounds

Users should create a new Unpacker instead of reusing the same Unpacker after an error occurs.

Applying the above patch can prevent SEGV, but reusing the Streaming Unpacker after it has encountered an error will not yield correct data. If an error occurs during Streaming Unpacking, the Stream and Streaming Unpacker should be discarded.

Therefore, this is not just a workaround but the correct solution. The above patch only prevents crashes from incorrect usage.

Database specific 
{
    "cwe_ids":  [
        "CWE-416"
    ],
    "github_reviewed":  true,
    "github_reviewed_at":  "2026-06-19T21:42:55Z",
    "nvd_published_at":  null,
    "severity":  "HIGH"
}
References

Affected packages

PyPI / msgpack

Package

Name
msgpack
View open source insights on deps.dev
Purl
pkg:pypi/msgpack

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
1.2.1

Affected versions

0.*
0.5.0
0.5.1
0.5.2
0.5.3
0.5.4
0.5.5
0.5.6
0.6.0
0.6.1
0.6.2
1.*
1.0.0rc1
1.0.0
1.0.1
1.0.2
1.0.3rc1
1.0.3
1.0.4rc1
1.0.4
1.0.5rc1
1.0.5
1.0.6rc1
1.0.6
1.0.7
1.0.8
1.1.0rc1
1.1.0rc2
1.1.0
1.1.1rc1
1.1.1
1.1.2
1.2.0rc1
1.2.0

Database specific

last_known_affected_version_range 
"<= 1.2.0"
source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-6v7p-g79w-8964/GHSA-6v7p-g79w-8964.json"