CVE-2026-66338

EUVD-2026-48752
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.
HTTP Request/Response Smuggling
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
5.4 MEDIUM
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 20.56%
Affected Products (NVD)
VendorProductVersion
gnomelibsoup
-
redhatenterprise_linux
6.0
redhatenterprise_linux
7.0
redhatenterprise_linux
8.0
redhatenterprise_linux
9.0
redhatenterprise_linux
10.0
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
libsoup2.4
bookworm
ignored
trixie
no-dsa
libsoup3
bookworm
ignored
forky
vulnerable
sid
3.8.0-2
fixed
trixie
no-dsa
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
libsoup2.4
bionic
deferred
focal
deferred
jammy
deferred
noble
deferred
resolute
deferred
stonking
deferred
xenial
deferred
libsoup3
jammy
deferred
noble
deferred
resolute
deferred
stonking
deferred
Amazon Linux logo
Amazon Linux Releases
Amazon Package
Release
libsoup
Amazon Linux 2
0:2.56.0-6.amzn2.0.9
fixed
Amazon Linux 2023
0:2.72.0-6.amzn2023.0.16
fixed
libsoup-debuginfo
Amazon Linux 2
0:2.56.0-6.amzn2.0.9
fixed
Amazon Linux 2023
0:2.72.0-6.amzn2023.0.16
fixed
libsoup-debugsource
Amazon Linux 2023
0:2.72.0-6.amzn2023.0.16
fixed
libsoup-devel
Amazon Linux 2
0:2.56.0-6.amzn2.0.9
fixed
Amazon Linux 2023
0:2.72.0-6.amzn2023.0.16
fixed
libsoup-doc
Amazon Linux 2023
0:2.72.0-6.amzn2023.0.16
fixed