Skip to content
Fencer Intel
low 3.9

CVE-2026-3632 json

Libsoup: libsoup: http smuggling and server-side request forgery via malformed hostnames

published 7mo ago modified 3d ago also EUVD-2026-12559

cvss
3.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 12%
public exploits
0
none known

Summary

A flaw was found in libsoup, a library used by applications to send network requests. This vulnerability occurs because libsoup does not properly validate hostnames, allowing special characters to be injected into HTTP headers. A remote attacker could exploit this to perform HTTP smuggling, where they can send hidden, malicious requests alongside legitimate ones. In certain situations, this could lead to Server-Side Request Forgery (SSRF), enabling an attacker to force the server to make unauthorized requests to other internal or external systems. The impact is low, as SoupServer is not actually used in internet infrastructure.

Is CVE-2026-3632 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-3632 updated cvss 3.9

libsoup: libsoup: HTTP Smuggling and Server-Side Request Forgery via Malformed Hostnames

  • Red Hat Enterprise Linux 6 libsoup
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 libsoup Red Hat Enterprise Linux 8 libsoup Red Hat Enterprise Linux 9 libsoup Red Hat Enterprise Linux 10 libsoup3
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
7mo ago

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 12% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • gitlab.gnome.org https://gitlab.gnome.org/GNOME/libsoup/-/issues/483 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 3.9 CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:L
NVD 3.1 5.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:L

Affected products

  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9

Classification

Weakness
  • CWE-1286 Improper Validation of Syntactic Correctness of Input

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.