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VulnerabilityPublished

CVE-2026-126066: NaturalIntelligence fast-xml-parser · Inefficient Algorithmic Complexity

Affects NaturalIntelligence fast-xml-parserSource CVE Database V5

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Not known to be exploited · CVSS 3.7 Low : upgrade to 5.12.0 when convenient.

Data as of 10 Nov 2026, 20:36 UTC

CVSS 3.1 base score
3.7Low
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (GitHub_M)CVSS 3.13.7
Patch
Available – fixed in 5.12.0
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 10 Nov 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 10 Nov 2026.

What to do

Upgrade NaturalIntelligence fast-xml-parser to 5.12.0.

Affected software

ProductAffectedFixed in
NaturalIntelligencefast-xml-parserAffected
  • <5.12.0
Fixed in
  • 5.12.0

AI-suggested

Upgrade fast-xml-parser to version 5.12.0 or later, where this issue is fixed. No other mitigation is required as the vulnerability is resolved in the official patch.

Description

CVE-2026-126066 is a vulnerability in NaturalIntelligence's fast-xml-parser prior to version 5.12.0. When the non-default stopNodes option is enabled, the parser's readStopNodeData() function repeatedly rescans input containing many tag fragments without a closing character, causing quadratic time complexity. This leads to CPU exhaustion and denial of service by blocking the Node.js event loop. The issue is fixed in version 5.12.0.

References

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