APScheduler's JSONSerializer and CBORSerializer are vulnerable to Remote Code Execution (RCE) via Insecure Deserialization
The advisory, in context
The JSONSerializer and CBORSerializer in APScheduler (all versions including 3.10.x and 4.0.0a5) are vulnerable to Remote Code Execution (RCE) via Insecure Deserialization. The unmarshal_object function allows for arbitrary class instantiation and state injection by dynamically importing modules and calling setstate on any class available in the Python environment. An attacker can exploit this by submitting a specially crafted JSON or CBOR payload to an application using these serializers
Affected packages
Start with the recorded fix for your release branch. Check your installed version and test compatibility before upgrading. Fixing this advisory does not rule out other vulnerabilities in the release.
From 4.0.0a1 through 4.0.0a6 (inclusive)
No fix recorded for this interval.
6 explicitly affected versions
4.0.0a1, 4.0.0a2, 4.0.0a3, 4.0.0a4, 4.0.0a5, 4.0.0a6
View affected-version evidence
{
"ranges": [
{
"events": [
{
"introduced": "4.0.0a1"
},
{
"last_affected": "4.0.0a6"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"4.0.0a1",
"4.0.0a2",
"4.0.0a3",
"4.0.0a4",
"4.0.0a5",
"4.0.0a6"
]
}References
- https://nvd.nist.gov/vuln/detail/CVE-2026-31072
- https://access.redhat.com/security/cve/CVE-2026-31072
- https://bugzilla.redhat.com/show_bug.cgi?id=2479907
- https://gist.github.com/nedlir/11fb77f35a59cbba73392a086b02a9c6
- https://github.com/agronholm/apscheduler
- https://github.com/pypa/advisory-database/tree/main/vulns/apscheduler/PYSEC-2026-282.yaml
- https://pypi.org/project/apscheduler
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-31072.json