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🛡️ CVE-2026-44664 — fast-xml-builder

🟡 CVSS 6.1 — Medium ✅ No Known Exploit CWE-91 NVD
6.1
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

fast-xml-builder Comment Value regex can be bypassed

# Summary

The fix for https://github.com/advisories/GHSA-gh4j-gqv2-49f6 in fast-xml-parser sanitizes -- sequences in XML comment content using .replace(/--/g, '- -'). This skip the values containing three consecutive dashes (e.g., --->...), allowing an attacker to break out of an XML comment and inject arbitrary XML/HTML content.

Impact

Any application with comment property enabled allow attacker to inject malicious or unwanted code like JS script tag in the XML/HTML output.

Workarounds

Check for the presence of 3 consecutive dashes externally in the property value used for comment tag.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. A user must be tricked into taking some action. The scope is changed, meaning a successful attack can affect components beyond the vulnerable one. Rated impact: confidentiality low, integrity low, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: Required — someone has to click, open or visit something.
  • Scope: Changed — a successful attack reaches components beyond the vulnerable one.
  • Confidentiality impact: Low — limited, and the attacker does not choose what is affected.
  • Integrity impact: Low — limited, and the attacker does not choose what is affected.
  • Availability impact: None.

Weakness class

CVE-2026-44664 is classified as CWE-91: XML Injection. Untrusted data is inserted into an XML document or query, changing its structure rather than only its content.

Affected software

CVE-2026-44664 is recorded against 2 packages.

  • fast-xml-builder
  • unknown

Timeline and source

Published on 8 May 2026 and last revised on 14 May 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com (Web)
github.com (Web)
nvd.nist.gov (Advisory)
github.com (Package)

Other advisories for this package

fast-xml-builder has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-91: XML Injection) in other software:

CVE-2026-44664 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Medium
CVSS Score 6.1
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CWE CWE-91
Public Exploit ✅ No
Source NVD
Published 2026-05-08
Updated 2026-08-20
Modified 2026-05-14
Fix URL N/A

Affected Packages

Software From version Fixed in
fast-xml-builder — —
unknown — —

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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