CVE-2026-44660: high-severity vulnerability in ultrajson
UltraJSON: Memory Leak in ujson.dump() on Write Failure
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.7epss 0.4%
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:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Affected products
ultrajson · ultrajsonRelated CVEs — ultrajson
In the same product, most dangerous first.
CVE-2022-31116HIGHIncorrect handling of invalid surrogate pair characters in ujsonEPSS 2.5%CVE-2022-31117MEDIUMDouble free of buffer during string decoding in ujsonEPSS 1.9%CVE-2026-32874HIGHUltraJSON has a Memory Leak parsing large integers allows DoSEPSS 0.5%CVE-2026-32875HIGHUltraJSON has an integer overflow handling large indent leads to buffer overflow or infinite loopEPSS 0.5%CVE-2026-54911MEDIUMUltraJSON: Malformed/Truncated UTF-8 Accepted and Silently Rewritten in ujson.dumps()EPSS 0.4%