What’s Vulnerable › Vulnerabilities

CVE-2026-1801: Libsoup: libsoup: http request smuggling via malformed chunk headers

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-02-03 · updated 2026-06-17
• Weakness: CWE-444

Description

A flaw was found in libsoup, an HTTP client/server library. This HTTP Request Smuggling vulnerability arises from non-RFC-compliant parsing in the soup_filter_input_stream_read_line() logic, where libsoup accepts malformed chunk headers, such as lone line feed (LF) characters instead of the required carriage return and line feed (CRLF). A remote attacker can exploit this without authentication or user interaction by sending specially crafted chunked requests. This allows libsoup to parse and process multiple HTTP requests from a single network message, potentially leading to information disclosure.

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-2026-1801
• https://bugzilla.redhat.com/show_bug.cgi?id=2436315
• https://gitlab.gnome.org/GNOME/libsoup/-/issues/481

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