XXE in Http4s Http4s-Scala-Xml

CVE-2026-61741

http4s-scala-xml provides `EntityDecoder[F, scala.xml.Elem]` instances that parse XML message bodies. Prior to versions 0.24.1 and 1.0.0-M39, these decoders used a `javax.xml.parsers.SAXParserFactory` obtained from `SAXParserFactory.newInstance` without any security configuration. With the JDK's default settings, the parser resolves DOCTYPE declarations, external general and parameter entities, and external DTDs.An application that uses these decoders to parse untrusted XML is vulnerable to XML External Entity (XXE) attacks. An attacker can craft a request that discloses local files readable by the service process, performs server-side request forgery (SSRF) against internal network resources, and/or causes denial of service through entity expansion. Versions 0.24.1 and 1.0.0-M39 fix the issue.

Vulnerability class: XXE (XML External Entity)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 9.3 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:L.

EPSS exploit prediction

EPSS: 0.003 (22.2th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 22nd percentile — 22.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-61741: held from 0.003 to 0.003.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-61741?
CVE-2026-61741 is a critical-severity vulnerability in Http4s Http4s-Scala-Xml, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 9.3/10. Published 2026-09-24.
How severe is CVE-2026-61741?
Critical severity. CVSS v3 base score is 9.3 out of 10.