CVE-2026-31072
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedThe 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
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceAPScheduler's JSONSerializer and CBORSerializer contain an insecure deserialization vulnerability in the unmarshal_object function that allows attackers to dynamically import arbitrary modules and invoke __setstate__ on any Python class, enabling full remote code execution via specially crafted JSON or CBOR payloads.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify APScheduler installation and versionRun 'pip show apscheduler' or check your dependency manifest for the installed APScheduler versionAffected if The installed version contains the vulnerable unmarshal_object function in JSONSerializer/CBORSerializer (compare against known affected versions)
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Locate JSONSerializer or CBORSerializer usageSearch codebase for imports of 'apscheduler.schedulers.background' or similar and usages of JSONSerializer/CBORSerializer classesAffected if Code imports or instantiates JSONSerializer or CBORSerializer from APScheduler
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Identify unmarshal_object functionSearch for the unmarshal_object function in APScheduler's serialization module or inspect the installed package files for this functionAffected if The unmarshal_object function is present and handles deserialization without type validation
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Check data source trust levelExamine how the serializer is invoked - identify if it processes data from HTTP requests, user uploads, message queues, external APIs, or other untrusted sourcesAffected if JSONSerializer or CBORSerializer processes data from untrusted or attacker-controlled sources
User is affected if APScheduler with vulnerable serializer classes is installed AND those serializers process untrusted JSON or CBOR data without strict type allowlisting.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUntil an official patch is available, do not expose these serializers to untrusted input; replace with safer serialization formats (e.g., standard JSON with schema validation) and implement strict input allow-listing.
- Consultation10.0 h
- Implementation20.0 h
- Testing12.0 h
- Review / QA6.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $13,568.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-31072 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-31072 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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