fall back to utf-8 for invalid content-type charset#3427
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Response.charset() and feign-form's FormEncoder.getCharset() passed the parsed charset token straight to Charset.forName, so an unsupported or illegal name from a Content-Type header threw instead of using the documented UTF-8 default. Catch the charset exceptions in both and fall back to UTF-8, as FeignException.getResponseCharset already does.
velo
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Jun 19, 2026
velo
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This is a focused fix: Response.charset() and FormEncoder now both fall back to UTF-8 for illegal or unsupported charset tokens, and the new tests cover the two failure paths in core and feign-form. I do not see a compatibility or security issue here.
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Repro: a server response with
Content-Type: text/plain; charset=made-up-99(or an illegal name such ascharset=@) reachesResponse.charset(), which is called by every JSON/text decoder (jackson,json,fastjson2,jackson-jr,jackson3) throughresponse.body().asReader(response.charset()).Expected:
charset()returns its documented UTF-8 default.Actual:
UnsupportedCharsetException/IllegalCharsetNameExceptionescapes the decoder on an otherwise valid response.Cause:
Response.charset()hands the charset token parsed out of the header straight toCharset.forNamewith no guard.feign-form'sFormEncoder.getCharsethas the same unguarded call on the requestContent-Type.FeignException.getResponseCharsetalready guards the identical parse.Fix: catch
IllegalCharsetNameException/UnsupportedCharsetExceptionin both helpers and fall back to UTF-8. Regression tests cover both an illegal and an unsupported charset name.