CVE-2026-44660

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 66% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Elevated
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.5Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
7.5
EG Score
7.5(medium)
EPSS
34.4%
KEV
Not listed

Published

May 27, 2026

Last Modified

June 2, 2026

Advisory Details (3)

Auto-updated Jun 2, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit, github_release.
github Patch Available🟡 PoC Available

Memory Leak in ujson.dump() on Write Failure · Advisory · ultrajson/ultrajson · GitHub

https://github.com/ultrajson/ultrajson/security/advisories/GHSA-c38f-wx89-p2xg
github_release Patch Available

5.12.1

Patch available: ultrajson/ultrajson 5.12.1

https://github.com/ultrajson/ultrajson/releases/tag/5.12.1
github_commit Patch Available

commit 82af1d0ac01d (ultrajson/ultrajson)

Patch available: ultrajson/ultrajson 5.12.1 (contains commit 82af1d0ac01d)

https://github.com/ultrajson/ultrajson/commit/82af1d0ac01d09aa40c887b460d44b9d9f4bccd9

Vendor Advisories for CVE-2026-44660(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
ujson1.15 ... 5.9.0 (40 versions)5.12.1—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 6× in last 7d / 28× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-22 14:08 UTCEPSS rescore
  2. 2026-07-21 15:24 UTCEPSS rescore
  3. 2026-07-20 17:08 UTCEPSS rescore
  4. 2026-07-19 02:29 UTCEPSS rescore
  5. 2026-07-18 10:04 UTCEPSS rescore
  6. 2026-07-16 17:03 UTCEPSS rescore
  7. 2026-07-15 16:57 UTCEPSS rescore
  8. 2026-07-15 02:00 UTCEPSS rescore
  9. 2026-07-13 22:30 UTCEPSS rescore
  10. 2026-07-13 06:13 UTCEPSS rescore
  11. 2026-07-12 05:46 UTCEPSS rescore
  12. 2026-07-11 08:27 UTCEPSS rescore
  13. 2026-07-09 19:10 UTCEPSS rescore
  14. 2026-07-08 15:16 UTCEPSS rescore
  15. 2026-07-07 13:46 UTCEPSS rescore
  16. 2026-07-06 16:27 UTCEPSS rescore
  17. 2026-07-06 02:23 UTCEPSS rescore
  18. 2026-07-05 02:30 UTCEPSS rescore
  19. 2026-07-04 06:31 UTCEPSS rescore
  20. 2026-07-01 15:07 UTCEPSS rescore
  21. 2026-06-30 23:22 UTCEPSS rescore
  22. 2026-06-28 14:07 UTCEPSS rescore
  23. 2026-06-28 04:56 UTCEPSS rescore
  24. 2026-06-27 03:08 UTCEPSS rescore
  25. 2026-06-25 13:49 UTCEPSS rescore
Show 45 more
  1. 2026-06-25 13:49 UTCEPSS rescore
  2. 2026-06-24 14:05 UTCEPSS rescore
  3. 2026-06-23 21:33 UTCEPSS rescore
  4. 2026-06-22 14:25 UTCEPSS rescore
  5. 2026-06-22 14:25 UTCEPSS rescore
  6. 2026-06-21 14:56 UTCEPSS rescore
  7. 2026-06-21 14:56 UTCEPSS rescore
  8. 2026-06-21 01:59 UTCEPSS rescore
  9. 2026-06-19 19:25 UTCEPSS rescore
  10. 2026-06-18 17:52 UTCEPSS rescore
  11. 2026-06-18 17:52 UTCEPSS rescore
  12. 2026-06-17 17:53 UTCEPSS rescore
  13. 2026-06-16 17:52 UTCEPSS rescore
  14. 2026-06-15 17:49 UTCEPSS rescore
  15. 2026-06-13 23:00 UTCEPSS rescore
  16. 2026-06-12 23:12 UTCEPSS rescore
  17. 2026-06-12 23:12 UTCEPSS rescore
  18. 2026-06-11 14:00 UTCEPSS rescore
  19. 2026-06-10 22:18 UTCEPSS rescore
  20. 2026-06-10 13:22 UTCEPSS rescore
  21. 2026-06-10 13:22 UTCEPSS rescore
  22. 2026-06-08 14:17 UTCEPSS rescore
  23. 2026-06-08 14:17 UTCEPSS rescore
  24. 2026-06-07 15:25 UTCEPSS rescore
  25. 2026-06-07 15:25 UTCEPSS rescore
  26. 2026-06-06 13:47 UTCEPSS rescore
  27. 2026-06-06 13:47 UTCEPSS rescore
  28. 2026-06-05 22:47 UTCEPSS rescore
  29. 2026-06-05 06:10 UTCEPSS rescore
  30. 2026-06-05 06:10 UTCEPSS rescore
  31. 2026-06-04 13:12 UTCEPSS rescore
  32. 2026-06-04 13:12 UTCEPSS rescore
  33. 2026-06-03 05:08 UTCEG score recompute▼ 1.20
  34. 2026-06-02 20:13 UTCEPSS rescore
  35. 2026-06-01 13:52 UTCEPSS rescore
  36. 2026-06-01 13:52 UTCEPSS rescore
  37. 2026-05-31 22:30 UTCEPSS rescore
  38. 2026-05-31 22:30 UTCEPSS rescore
  39. 2026-05-31 00:16 UTCEPSS rescore
  40. 2026-05-31 00:16 UTCEPSS rescore
  41. 2026-05-29 13:44 UTCEPSS rescore
  42. 2026-05-29 13:44 UTCEPSS rescore
  43. 2026-05-28 13:44 UTCEPSS rescore
  44. 2026-05-28 13:44 UTCEPSS rescore
  45. 2026-05-27 22:19 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-44660?
CVE-2026-44660 is a high vulnerability published on May 27, 2026. 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…
When was CVE-2026-44660 disclosed?
CVE-2026-44660 was first published in the National Vulnerability Database on May 27, 2026, with the most recent update on June 2, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-44660 actively exploited?
CVE-2026-44660 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 34.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-44660?
CVE-2026-44660 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-44660?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-44660, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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