Amazon Linux 2023 Security Advisory: ALAS2023-2026-3421
Advisory Released Date: 2026-11-12
Advisory Updated Date: 2026-11-12
FAQs regarding Amazon Linux ALAS/CVE Severity
A flaw was found in libsoup. The soup_uri_decode_data_uri() function incorrectly treated base64 data-URI payloads as NUL-terminated strings when calling g_base64_decode_inplace(). If the percent-decoded payload contained embedded NUL bytes, the decoded length could remain uninitialized and be used as the size of the returned GBytes. This can lead to an out-of-bounds read or application crash when processing a crafted data URI. (CVE-2026-102555)
A flaw was found in libsoup. When handling an incoming WebSocket Pong frame, SoupWebsocketConnection emitted the ::pong signal with a GByteArray pointer even though the signal is declared to pass a GBytes. Applications connecting a handler that follows the documented GBytes API can trigger heap corruption or a crash upon receiving a crafted Pong. (CVE-2026-102556)
A flaw was found in libsoup. When reassembling fragmented WebSocket messages into a GByteArray, libsoup did not adequately cap total message size against the limits of the underlying buffer type. A remote peer could send fragments that caused size truncation while the implementation still used the full length, leading to heap corruption or a crash. (CVE-2026-102557)
A flaw was found in libsoup. When max-incoming-payload-size is unlimited (0), SoupWebsocketConnection could grow its incoming GByteArray based on an attacker-controlled frame length until the length wrapped, causing a heap buffer overflow while reading frame data. (CVE-2026-102558)
A flaw was found in libsoup. When constructing a masked WebSocket client frame for a very large outgoing payload, size values passed to GByteArray allocation APIs could be truncated while the masking routine still used the full length, causing a heap buffer overflow. (CVE-2026-102559)
A flaw was found in libsoup. When the permessage-deflate WebSocket extension compresses a very large outgoing message, truncated size calculations used for GByteArray growth could wrap, causing zlib to write past the allocated buffer and resulting in a heap buffer overflow. (CVE-2026-102560)
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. (CVE-2026-103399)
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-2026-66337)
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-2026-66338)
Affected Packages:
libsoup3
Issue Correction:
Run dnf update libsoup3 --releasever 2023.12.20261112 or dnf update --advisory ALAS2023-2026-3421 --releasever 2023.12.20261112 to update your system.
More information on how to update your system can be found on this page: Amazon Linux 2023 documentation
aarch64:
libsoup3-debuginfo-3.7.3-1.amzn2023.aarch64
libsoup3-devel-3.7.3-1.amzn2023.aarch64
libsoup3-3.7.3-1.amzn2023.aarch64
libsoup3-debugsource-3.7.3-1.amzn2023.aarch64
noarch:
libsoup3-doc-3.7.3-1.amzn2023.noarch
src:
libsoup3-3.7.3-1.amzn2023.src
x86_64:
libsoup3-debuginfo-3.7.3-1.amzn2023.x86_64
libsoup3-devel-3.7.3-1.amzn2023.x86_64
libsoup3-3.7.3-1.amzn2023.x86_64
libsoup3-debugsource-3.7.3-1.amzn2023.x86_64