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Undertow: undertow: chunkreader message length permits chunk-size overflow

CVSS 3.1 6.5 MEDIUMCheck source for fixed versionsKEV status unknown

cve-program · CVE-2026-91920

Published

A flaw was found in the ChunkReader component of the Undertow web server, which is used to handle chunked transfer encoding in HTTP requests. The issue occurs because a security check for the chunk size is performed before the value is shifted, allowing a specifically crafted 15-digit chunk size to bypass the limit and overflow into internal state flags. This can cause the server to terminate a request body prematurely and interpret the remaining data as a separate, smuggled request.

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CVE-2026-91920 · CVE overview and exploitation status

cve-program · CVE-2026-91920

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Sources read 13 Nov 06:11 UTC · 274 of 275 readable · 272 fully read · documentation 469/469 current