Hash collision in typelevel jawn

Impact

Extenders of the org.typelevel.jawn.SimpleFacade and org.typelevel.jawn.MutableFacade who don't override objectContext() are vulnerable to a hash collision attack. Most applications do not implement these traits directly, but inherit from a library:

Affected implementations include:

• org.http4s :: http4s-play-json
• org.typelevel :: jawn-ast (< 0.8.0)
• org.typelevel :: jawn-play (discontinued)
• org.typelevel :: jawn-rojoma (discontinued)
• org.typelevel :: jawn-spray (discontinued)

Unaffected implementations include:

• io.argonaut :: argonaut-jawn
• io.circe :: circe-parser
• org.typelevel :: jawn-ast (>= 0.8.0)
• org.typelevel :: jawn-json4s (discontinued)
• org.typelevel :: jawn-argonaut (discontinued)

Patches

jawn-parser-1.3.2 fixes the issue.

Workarounds

Override objectContext() to use a collision-safe collection. See the patch for an example in both SimpleFacade and MutableFacade.

References

• https://github.com/typelevel/jawn/pull/390

Credits

• @kag0, for the report and the patch

For more information

If you have any questions or comments about this advisory:

• Open an issue in typelevel/jawn
• E-mail a maintainer:
  • @rossabaker