HOMEVULNERABILITIESCVE-2026-44660
HIGH

CVE-2026-44660

CWE-401Published: May 27, 2026· Updated: Jun 2, 2026

7.5
CVSS v3.1
EPSS:0.04%probability of exploitation in 30 daysPercentile:12.4th

Official Description

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.

NVD Source

Technical Analysis

CVE-2026-44660 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 7.5.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected Vendors & Products

ultrajson_project1 product
ultrajson
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://github.com/ultrajson/ultrajson/commit/82af1d0ac01d09aa40c887b460d44b9d9f4bccd9
PATCHhttps://github.com/ultrajson/ultrajson/security/advisories/GHSA-c38f-wx89-p2xg
PATCHhttps://github.com/ultrajson/ultrajson/security/advisories/GHSA-c38f-wx89-p2xg

All References (4)

→
https://github.com/ultrajson/ultrajson/commit/82af1d0ac01d09aa40c887b460d44b9d9f4bccd9Patch
→
https://github.com/ultrajson/ultrajson/releases/tag/5.12.1Product · Release Notes
→
https://github.com/ultrajson/ultrajson/security/advisories/GHSA-c38f-wx89-p2xgExploit · Mitigation · Patch · Vendor Advisory
→
https://github.com/ultrajson/ultrajson/security/advisories/GHSA-c38f-wx89-p2xgExploit · Mitigation · Patch · Vendor Advisory

Quick Facts

CVE IDCVE-2026-44660
CVSS Score7.5 / 10
SeverityHIGH
WeaknessCWE-401
CISA KEVNo
EPSS (30d)0.04%
Affected1 vendor
PublishedMay 27, 2026

Related CVEs (CWE-401)

CVE-2026-0646
8.7
CVE-2026-20012
8.6
CVE-2026-20014
7.7
CVE-2026-20105
7.7
CVE-2026-35424
7.5
CVE-2026-3650
7.5

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2026-44660 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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