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CVE-2026-44660

8.7
High
EPSS 0.42%Patch availableMay 28, 2026

ujson memory leak on write error (pre-5.12.1), may cause DoS via memory exhaustion.

common questions

Is CVE-2026-44660 being exploited?

Not confirmed. CVE-2026-44660 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.42% probability of exploitation in the next 30 days.

How severe is CVE-2026-44660?

CVE-2026-44660 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2026-44660?

Yes. A fix has been recorded for CVE-2026-44660. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.

What does CVE-2026-44660 affect?

CVE-2026-44660 affects UltraJSON (ujson) < 5.12.1, Python apps using ujson library. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

What should I do about CVE-2026-44660?

Upgrade to 5.12.1 or later

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

executive summary
technical analysis
affected
UltraJSON (ujson) < 5.12.1Python apps using ujson library
impact

Memory not decremented after failed dump; attacker can exhaust memory via crafted payloads, causing DoS/crash.

action required

Patch when possible

affected versions
ultrajson ultrajson
  • affected< 5.12.1

As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.

how to fix
Remediation steps are tailored for users whose stack is affected. Add this technology to your stack to see the fix checklist.
references
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