What is CVE-2026-32874?

CVE-2026-32874 is a high-severity vulnerability in Ultrajson, classified under Missing Release of Memory after Effective Lifetime. CVSS score: 7.5/10. Published 2026-03-20.

How severe is CVE-2026-32874?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Ultrajson

CVE-2026-32874

UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+. Versions 5.4.0 through 5.11.0 contain an accumulating memory leak in JSON parsing large (outside of the range [-2^63, 2^64 - 1]) integers. The le…

EPSS: 0.001 (23.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Ultrajson — versions >= 5.4.0, < 5.12.0

Weakness classification (CWE)

CWE-401 — Missing Release of Memory after Effective Lifetime

References

https://github.com/ultrajson/ultrajson/security/advisories/GHSA-wgvc-ghv9-3pmm (x_refsource_CONFIRM)
https://github.com/ultrajson/ultrajson/commit/4baeb950df780092bd3c89fc702a868e99a3a1d2 (x_refsource_MISC)
https://github.com/ultrajson/ultrajson/releases/tag/5.12.0 (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-32874?: CVE-2026-32874 is a high-severity vulnerability in Ultrajson, classified under Missing Release of Memory after Effective Lifetime. CVSS score: 7.5/10. Published 2026-03-20.
How severe is CVE-2026-32874?: High severity. CVSS v3 base score is 7.5 out of 10.