CVE-2026-44660

Summary

UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+. Prior to 5.12.1, when ujson.dump() writes to a file-like object and the write operation raises an exception, the serialized JSON string object is not decremented, leaking memory. Each failed write operation leaks the full size of the serialized payload. This vulnerability is fixed in 5.12.1.

Affected Software

Weaknesses

• CWE-401: CWE-401: Missing Release of Memory after Effective Lifetime

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: poc
  • Automatable: yes
  • Technical Impact: partial

Additional References

• https://github.com/ultrajson/ultrajson/security/advisories/GHSA-c38f-wx89-p2xg

References

• https://github.com/ultrajson/ultrajson/security/advisories/GHSA-c38f-wx89-p2xg
• https://github.com/ultrajson/ultrajson/commit/82af1d0ac01d09aa40c887b460d44b9d9f4bccd9
• https://github.com/ultrajson/ultrajson/releases/tag/5.12.1

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