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: 8.71%
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
vulnerable
trixie
no-dsa
libsoup3
bookworm
vulnerable
forky
vulnerable
sid
vulnerable
trixie
no-dsa
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
libsoup2.4
bionic
needs-triage
focal
needs-triage
jammy
needs-triage
noble
needs-triage
resolute
needs-triage
xenial
needs-triage
libsoup3
jammy
needs-triage
noble
needs-triage
resolute
needs-triage