Vulnerability · Published Feb 3, 2026 · Assigned by redhat
CVE-2026-1801Libsoup: libsoup: http request smuggling via malformed chunk headers
Medium 5.3
In plain English
A medium-severity security flaw in Red Hat Enterprise Linux 10 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | libsoup2.4 | no fix listed | DEBIAN-CVE-2026-1801 |
| Debian:13 | libsoup2.4 | no fix listed | DEBIAN-CVE-2026-1801 |
| Debian:12 | libsoup3 | no fix listed | DEBIAN-CVE-2026-1801 |
| Debian:13 | libsoup3 | no fix listed | DEBIAN-CVE-2026-1801 |
| Ubuntu:22.04:LTS | libsoup2.4 | 2.74.2-3ubuntu0.8 | USN-8780-1 |
| Ubuntu:22.04:LTS | libsoup2.4 | 2.74.2-3ubuntu0.8 | UBUNTU-CVE-2026-1801 |
| Ubuntu:24.04:LTS | libsoup2.4 | 2.74.3-6ubuntu1.8 | UBUNTU-CVE-2026-1801 |
| Ubuntu:24.04:LTS | libsoup2.4 | 2.74.3-6ubuntu1.8 | USN-8780-1 |
| Ubuntu:25.10 | libsoup2.4 | no fix listed | UBUNTU-CVE-2026-1801 |
| Ubuntu:26.10 | libsoup2.4 | no fix listed | UBUNTU-CVE-2026-1801 |
| Ubuntu:24.04:LTS | libsoup3 | 3.4.4-5ubuntu0.8 | UBUNTU-CVE-2026-1801 |
| Ubuntu:24.04:LTS | libsoup3 | 3.4.4-5ubuntu0.8 | USN-8780-1 |
| Ubuntu:25.10 | libsoup3 | no fix listed | UBUNTU-CVE-2026-1801 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Red Hat | Red Hat Enterprise Linux 10 | see references |
| Red Hat | Red Hat Enterprise Linux 6 | see references |
| Red Hat | Red Hat Enterprise Linux 7 | see references |
| Red Hat | Red Hat Enterprise Linux 8 | see references |
| Red Hat | Red Hat Enterprise Linux 9 | see references |
Weakness: CWE-444 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
References
- https://access.redhat.com/security/cve/CVE-2026-1801 vdb-entry, x_refsource_REDHAT
- RHBZ#2436315 issue-tracking, x_refsource_REDHAT
- https://gitlab.gnome.org/GNOME/libsoup/-/issues/481