Impact
Servlets with multipart support (e.g. annotated with @MultipartConfig) that call HttpServletRequest.getParameter() or HttpServletRequest.getParts() may cause OutOfMemoryError when the client sends a multipart request with a part that has a name but no filename and a very large content.
This happens even with the default settings of fileSizeThreshold=0 which should stream the whole part content to disk.
An attacker client may send a large multipart request and cause the server to throw OutOfMemoryError.
However, the server may be able to recover after the OutOfMemoryError and continue its service -- although it may take some time.
A very large number of parts may cause the same problem.
Patches
Patched in Jetty versions
- 9.4.51.v20230217 - via PR #9345
- 10.0.14 - via PR #9344
- 11.0.14 - via PR #9344
Workarounds
Multipart parameter maxRequestSize must be set to a non-negative value, so the whole multipart content is limited (although still read into memory).
Limiting multipart parameter maxFileSize won't be enough because an attacker can send a large number of parts that summed up will cause memory issues.
References
lachlan-roberts Analyst
Impact
Servlets with multipart support (e.g. annotated with
@MultipartConfig) that callHttpServletRequest.getParameter()orHttpServletRequest.getParts()may causeOutOfMemoryErrorwhen the client sends a multipart request with a part that has a name but no filename and a very large content.This happens even with the default settings of
fileSizeThreshold=0which should stream the whole part content to disk.An attacker client may send a large multipart request and cause the server to throw
OutOfMemoryError.However, the server may be able to recover after the
OutOfMemoryErrorand continue its service -- although it may take some time.A very large number of parts may cause the same problem.
Patches
Patched in Jetty versions
Workarounds
Multipart parameter
maxRequestSizemust be set to a non-negative value, so the whole multipart content is limited (although still read into memory).Limiting multipart parameter
maxFileSizewon't be enough because an attacker can send a large number of parts that summed up will cause memory issues.References