generate multipart boundary from SecureRandom#3429
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velo
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Good security hardening for multipart boundaries. The switch in form/src/main/java/feign/form/MultipartFormContentProcessor.java keeps the existing wire format simple while removing the predictable clock-derived boundary, and MultipartBoundaryTest covers the regression. CI is green and I do not see a compatibility issue here.
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Repro:
MultipartBoundaryTestdrivesMultipartFormContentProcessor.processand reads the boundary back out of the generatedContent-Typeheader; on the current code it equalsLong.toHexString(System.currentTimeMillis())for the millisecond the request was built.Cause: the boundary is derived from the wall clock, so it is low-entropy and guessable. RFC 2046 needs the boundary to never appear in a part, and against attacker-controlled body bytes the only guarantee is that the delimiter is unpredictable. A caller forwarding untrusted data into a field or filename value can embed
\r\n--<boundary>and inject or truncate parts, which theContent-Dispositionescaping in #3417 cannot cover because part bodies are written verbatim.Fix: build the boundary from a shared
SecureRandomas 128-bit lowercase hex.