CVE-2026-30830: Defuddle: XSS via unescaped string interpolation in _findContentBySchemaText image tag

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-03-07 · updated 2026-06-17
Weakness: CWE-79

Description

Defuddle cleans up HTML pages. Prior to version 0.9.0, the _findContentBySchemaText method in src/defuddle.ts interpolates image src and alt attributes directly into an HTML string without escaping. An attacker can use a " in the alt attribute to break out of the attribute context and inject event handler. This issue has been patched in version 0.9.0.

Affected products

kepano defuddle: before 0.9.0 — fixed in 0.9.0

How to fix

Upgrade to a fixed version: kepano defuddle 0.9.0. Check the vendor advisory for mitigations.

References

https://github.com/kepano/defuddle/commit/f154cb740ee603431b69638273af737a27156df9
https://github.com/kepano/defuddle/security/advisories/GHSA-5mq8-78gm-pjmq

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