CVE-2026-3633: Libsoup: libsoup: header and http request injection via crlf injection

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-03-17 · updated 2026-06-17
Weakness: CWE-93

Description

A flaw was found in libsoup. A remote attacker, by controlling the method parameter of the `soup_message_new()` function, could inject arbitrary headers and additional request data. This vulnerability, known as CRLF (Carriage Return Line Feed) injection, occurs because the method value is not properly escaped during request line construction, potentially leading to HTTP request injection.

Affected products

GNOME libsoup: all versions
Red Hat Enterprise Linux: 6.0, 7.0, 8.0, 9.0, 10.0

References

https://access.redhat.com/security/cve/CVE-2026-3633
https://bugzilla.redhat.com/show_bug.cgi?id=2445128
https://gitlab.gnome.org/GNOME/libsoup/-/issues/484

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