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CRITICAL severity

jsonpickle unsafe deserializationGHSA-j66q-qmrc-89rx

CRITICAL

GHSA-j66q-qmrc-89rx is a critical-severity (CVSS 9.8) Deserialization of Untrusted Data vulnerability in jsonpickle. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.

Also known asCVE-2020-22083PYSEC-2020-49
Published
Updated
Affected
1 pkg
Patched
See advisory
Exploits
1 known
Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
6.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs94th percentile — riskier than 94% of all scored CVEsHighest risk
4.16%5.12%6.08%7.03%4.7%6.5%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐍jsonpickle

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

jsonpickle through 1.4.1 allows remote code execution during deserialization of a malicious payload through the decode() function. Note: It has been argued that this is expected and clearly documented behaviour. pickle is known to be capable of causing arbitrary code execution, and must not be used with un-trusted data

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
🐍PyPIjsonpickleall versionsNo fix

Affected Products

1 product · 1 configurations
Application
jsonpicklejsonpickle_project
≤ 1.4.1
range
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

jsonpickle through 1.4.1 allows remote code execution during deserializa…

versprite.comNVDDec 2020

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jsonpickle, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Remediation status

    The records we use list no patched version of jsonpickle for GHSA-j66q-qmrc-89rx. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.

  3. Mitigate without a patch

    Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Frequently Asked Questions

jsonpickle through 1.4.2 allows remote code execution during deserialization of a malicious payload through the `decode()` function. This CVE is disputed by the project author as intended functionality.
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GHSA-j66q-qmrc-89rx: jsonpickle RCE (Critical 9.8)