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VulnerabilityPublished Updated

CVE-2026-44660: Pandas · UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+

Affects pandasSource GCVE Database

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Not known to be exploited · CVSS 7.5 High · fixed in 5.12.1 : patch pandas soon.

Data as of 9 Nov 2026, 14:18 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 5.12.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 9 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 26.10pandaspkg:deb/ubuntu/pandas?arch=source&distro=stonkingOther threatsAffected
  • =2.3.3+dfsg-3ubuntu1
  • =2.3.3+dfsg-3ubuntu3
Fixed in–
Ubuntu 26.10ujsonpkg:deb/ubuntu/ujson?arch=source&distro=stonkingOther threatsAffected
  • =5.11.0-3build1
  • =5.13.0-1
Fixed in–
Ubuntu 26.04 LTSujsonpkg:deb/ubuntu/ujson?arch=source&distro=resoluteOther threatsAffected
  • 5.10.0-1build2 – 5.11.0-3ubuntu0.1
5 affected builds
Fixed in–
Ubuntu 25.10pandaspkg:deb/ubuntu/pandas?arch=source&distro=questingOther threatsAffected
  • =2.2.3+dfsg-8build1
  • =2.2.3+dfsg-9
Fixed in–
Ubuntu 25.10ujsonpkg:deb/ubuntu/ujson?arch=source&distro=questingOther threatsAffected
  • =5.10.0-1build2
  • =5.10.0-1ubuntu0.1
Fixed in–
Ubuntu Pro 24.04 LTSujsonpkg:deb/ubuntu/ujson?arch=source&distro=esm-apps/nobleOther threatsAffected
  • 5.8.0-1 – 5.9.0-1ubuntu0.1~esm1
5 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade UltraJSON (ujson) to version 5.12.1 or later, where this memory leak issue is fixed. No other mitigation is required as the fix addresses the root cause.

Description

UltraJSON (ujson), a fast JSON encoder and decoder used with Python 3.7+, has a memory leak vulnerability in versions prior to 5.12.1. When ujson.dump() writes to a file-like object and the write operation fails with an exception, the serialized JSON string object is not properly decremented, causing memory to leak equal to the size of the payload. This issue is fixed in version 5.12.1.

References

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