CVE-2026-58055

EUVD-2026-39975
nghttp2's nghttpx proxy through 1.69.0 forwards an HTTP/1.1 Upgrade request that also carries a Content-Length header and body onto reusable keep-alive backend connections, re-adding the Upgrade and Connection headers while passing Content-Length verbatim. A backend that resolves the resulting ambiguous message in the attacker's favor enables HTTP request/response smuggling and cross-client response-queue poisoning.
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: 18.06%
Affected Products (NVD)
VendorProductVersion
nghttp2nghttp2
𝑥
≤ 1.69.0
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
nghttp2
bookworm
postponed
bookworm (security)
vulnerable
bullseye
postponed
bullseye (security)
vulnerable
forky
vulnerable
sid
vulnerable
trixie
no-dsa
trixie (security)
vulnerable
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
nghttp2
bionic
needs-triage
focal
needs-triage
jammy
Fixed 1.43.0-1ubuntu0.4
released
noble
Fixed 1.59.0-1ubuntu0.4
released
questing
Fixed 1.64.0-1.1ubuntu1.2
released
resolute
Fixed 1.68.0-2ubuntu0.2
released
openSUSE logo
openSUSE / SLES Releases
openSUSE Product
Release
libnghttp2-14
suse enterprise server 15 SP4
1.40.0-150200.25.1
fixed
libnghttp2-14-32bit
suse enterprise server 15 SP4
1.40.0-150200.25.1
fixed
libnghttp2-devel
suse enterprise server 15 SP4
1.40.0-150200.25.1
fixed
libnghttp2_asio-devel
suse enterprise desktop 15 SP7
1.40.0-150600.25.8.1
fixed
suse enterprise sap 15 SP7
1.40.0-150600.25.8.1
fixed
suse enterprise server 15 SP4
1.40.0-150200.25.1
fixed
suse enterprise server 15 SP7
1.40.0-150600.25.8.1
fixed
libnghttp2_asio1
suse enterprise desktop 15 SP7
1.40.0-150600.25.8.1
fixed
suse enterprise sap 15 SP7
1.40.0-150600.25.8.1
fixed
suse enterprise server 15 SP4
1.40.0-150200.25.1
fixed
suse enterprise server 15 SP7
1.40.0-150600.25.8.1
fixed
Azure Linux logo
Azure Linux Releases
Azure Package
Release
fluent-bit
Azure Linux 3.0
0:3.1.10-6.azl3
fixed