Defuddle: XSS via unescaped string interpolation in _findContentBySchemaText image tag

published 2026-03-06 8 mo ago modified 2026-07-20 3 mo ago also GHSA-5mq8-78gm-pjmq , EUVD-2026-10118

cvss: 6.1; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 21%
public exploits: 0; none known

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.

Patch / fix

fixed in 2 links 1

npm defuddle 0.9.0
kepano defuddle 0.9.0

github.com/kepano/defuddle@f154cb7 commit

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 8 mo ago (2026-03-10)

Exploit prediction

0.29% chance of exploitation in the next 30 days, higher than 21% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/kepano/defuddle/security/advisories/GHSA-5mq8-78gm-pjmq referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	2.1	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:P
CNA	4.0	2.1	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD	3.1	6.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
GitHub	3.1	6.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
npm	defuddle	<0.9.0	0.9.0

Affected products

kepano defuddle

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation

References

github.com /kepano/defuddle/commit/f154cb740ee603431b69638273af737a27156df9
web, patch
github.com /kepano/defuddle/security/advisories/GHSA-5mq8-78gm-pjmq
web, exploit, mitigation, vendor-advisory
nvd.nist.gov /vuln/detail/CVE-2026-30830
advisory
github.com /kepano/defuddle
package

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary