ALAS2027-2026-209

References: CVE-2026-102560  CVE-2026-102559  CVE-2026-102558  CVE-2026-102557  CVE-2026-102556  CVE-2026-102555 
FAQs regarding Amazon Linux ALAS/CVE Severity

Issue Overview:

Package updates are available for Amazon Linux 2027 that fix the following vulnerabilities:
CVE-2026-102560:
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-2026-102559:
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-2026-102558:
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-2026-102557:
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-2026-102556:
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-2026-102555:
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.

Issue Correction:
Run dnf update libsoup3 or dnf update --advisory ALAS2027-2026-209 to update your system.

New Packages:

aarch64:
    libsoup3-debuginfo-3.7.3-1.amzn2027.aarch64
    libsoup3-debugsource-3.7.3-1.amzn2027.aarch64
    libsoup3-devel-3.7.3-1.amzn2027.aarch64
    libsoup3-3.7.3-1.amzn2027.aarch64

noarch:
    libsoup3-doc-3.7.3-1.amzn2027.noarch

src:
    libsoup3-3.7.3-1.amzn2027.src

x86_64:
    libsoup3-debuginfo-3.7.3-1.amzn2027.x86_64
    libsoup3-devel-3.7.3-1.amzn2027.x86_64
    libsoup3-3.7.3-1.amzn2027.x86_64
    libsoup3-debugsource-3.7.3-1.amzn2027.x86_64