fast-xml-builder allows attribute values with unwanted quotes to bypass malicious or unwanted attributes

# Summary When an input data has quotes in attribute values but process entities is not enabled, it breaks the attribute value into multiple attributes. This gives the room for an attacker to insert unwanted attributes to the XML/HTML. ## Detail Malicious Input ``` { a: { "@_attr": '" onClick="alert(1)' } } ``` Output ```xml <a attr="" onClick="alert(1)"></a> ``` ### Workarounds If you're not ignoring attributes then keep processEntities flag true.

Source published

8 May 2026 16:29:10 UTC

Source modified

10 Sep 2026 03:51:04 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Publisher rating · HIGH