Summary
Package updates are available for Amazon Linux 2023 that fix the following vulnerabilities: CVE-2026-66338: A flaw was found in libsoup. The chunked transfer encoding parser uses a permissive parsing function for chunk sizes that silently accepts inputs violating RFC 9112, including leading whitespace, plus sign prefixes, and trailing invalid characters. When libsoup operates behind a strict frontend proxy, this parsing differential can be exploited to smuggle HTTP requests. CVE-2026-66337: A flaw was found in libsoup. An unsigned integer underflow in the soup_filter_input_stream_read_until() function causes a heap buffer over-read when parsing multipart HTTP responses. A malicious HTTP server can exploit this by sending a crafted multipart response, potentially causing the client application to crash or disclose sensitive heap memory. CVE-2026-103399: A flaw was found in SoupServer (libsoup). When an HTTP/1.x client sends a request with Expect: 100-continue and a request body, and SoupServer returns an early final (non-1xx) response before the body is read, the server neither drains the declared body bytes nor closes the connection. On a keep-alive connection, those leftover bytes are interpreted as a subsequent HTTP request. A remote, unauthenticated attacker can place a complete HTTP request in the body and cause SoupServer to process that smuggled request, leading to unintended request handling.
Fixed packages 5
| Release | Package | Fixed in |
|---|---|---|
| Amazon Linux · 2023 | libsoup3 | 0:3.7.3-1.amzn2023 |
| Amazon Linux · 2023 | libsoup3-debuginfo | 0:3.7.3-1.amzn2023 |
| Amazon Linux · 2023 | libsoup3-debugsource | 0:3.7.3-1.amzn2023 |
| Amazon Linux · 2023 | libsoup3-devel | 0:3.7.3-1.amzn2023 |
| Amazon Linux · 2023 | libsoup3-doc | 0:3.7.3-1.amzn2023 |
Vulnerabilities 3
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Medium 6.5
Libsoup: libsoup: heap buffer over-read via integer underflow in soup_filter_input_stream_read_until()
A flaw was found in libsoup. An unsigned integer underflow in the soup_filter_input_stream_read_until() function causes a heap buffer over-read when parsing multipart HTTP responses. A malicious HTTP server can exploit this by sending a crafted multipart resp…
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Medium 5.4
Libsoup: libsoup: http request smuggling via permissive chunk-size parsing in soup_body_input_stream_read_chunked()
A flaw was found in libsoup. The chunked transfer encoding parser uses a permissive parsing function for chunk sizes that silently accepts inputs violating RFC 9112, including leading whitespace, plus sign prefixes, and trailing invalid characters. When libso…
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Medium 5.3
Libsoup: soupserver: http/1 request smuggling via undrained expect: 100-continue body
A flaw was found in SoupServer (libsoup). When an HTTP/1.x client sends a request with Expect: 100-continue and a request body, and SoupServer returns an early final (non-1xx) response before the body is read, the server neither drains the declared body bytes…