Improper Restriction of Operations within the Bounds of a Memory Buffer in python-cjson

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

6.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2010-1666: 1.67% estimated exploitation activity in the next 30 days; percentile 76.76 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Buffer overflow in Dan Pascu python-cjson 1.0.5, when UCS-4 encoding is enabled, allows context-dependent attackers to cause a denial of service (application crash) or possibly have unspecified other impact via vectors involving crafted Unicode input to the cjson.encode function.

Published by the source

17 May 2022, 05:49 UTC

Last modified by the source

15 Oct 2024, 17:00 UTC

Source last checked

26 Oct 2026, 13:22 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-cqmh-mpx2-g633

2. Revision 2 · amended · 24 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-cqmh-mpx2-g633

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# Patch Next advisory brief: CVE-2010-1666

Advisory: Improper Restriction of Operations within the Bounds of a Memory Buffer in python-cjson
IDs: CVE-2010-1666, GHSA-cqmh-mpx2-g633
Record: https://patchnext.com/advisories/cve-2010-1666 (revision 3, source checked 26 Oct 2026, 13:22 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: python-cjson 1.0.5.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI python-cjson: affected <= 1.0.5; fixed in 1.0.5.1

## Suggested inspection (read-only)
- `python -m pip show python-cjson`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on python-cjson.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-cqmh-mpx2-g633 (OSV record GHSA-cqmh-mpx2-g633 lists affected ranges: PyPI python-cjson >=0 <1.0.5.1 (fixed))
- Verified: https://github.com/advisories/GHSA-cqmh-mpx2-g633 (GitHub-reviewed advisory GHSA-cqmh-mpx2-g633 lists affected ranges: PyPI python-cjson >=0 <=1.0.5)

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