8.7

CVE-2026-44660: ultrajson_project ultrajson

CVSS: 8.7v4.0HighAnalyzed
AliasesSUSE-SU-2026:23114-1SUSE-SU-2026:23136-1SUSE-SU-2026:3539-1
Published 27-05-2026Last modified 30-05-2026
Open JSON

Vulnerability summary

CVE-2026-44660 is a high (CVSS 8.7) vulnerability in ultrajson_project ultrajson. EPSS estimates a 0.64% chance of exploitation in the next 30 days, higher than 49.9% of scored vulnerabilities. 1 public exploit is recorded.

Overall risk
45/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.7/10
010
High · v4.0 (CVE.org)
EPSS score
0.64%
0%100%
Low · +0.22 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits1github

Advisory lineage

Upstream 0 · Downstream 0 · Related 1
CGA-MR59-CWRG-JQX9

Timeline

  1. 27-05-2026
    PublishedVulnerability first disclosed.
  2. 30-05-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

8 scores · 6 sources · 2 versions

EPSS trend

Probability

0.64%

Chance of exploitation in the next 30 days

Percentile

50%

Versus all other CVEs

30-day change

+0.22 pp

From 0.42% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.64%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

1 found
  • githubUnverified

    Ultrajson

    Maturity: poc

Weaknesses

CWE · root cause

Affected systems

Suse14 products
  • python-ujson&distro=SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS< 1.35-150100.3.13.1
  • python-ujson&distro=SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS< 1.35-150100.3.13.1
  • python-ujson&distro=SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS< 1.35-150100.3.13.1
  • python-ujson&distro=SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS< 1.35-150100.3.13.1
  • python-ujson&distro=SUSE Linux Enterprise Module for Development Tools 15 SP7< 1.35-150100.3.13.1
Ubuntu3 products
  • collada2gltfAll versions (No fix recorded)
  • pandasAll versions (No fix recorded)
  • ujsonAll versions (No fix recorded)
Chainguard1 product
  • label-studio< 1.23.0-r5
Debian1 product
  • ujsonAll versions (No fix recorded) | < 5.13.0-1
Opensuse1 product
  • python-ujson&distro=openSUSE Leap 16.0< 5.10.0-160000.3.1
PyPI1 product
  • ujson< 5.12.1
Ultrajson1 product
Ultrajson_project1 product

8 vendors · 23 products

References

14 links
Show all 14 references