# CVE-2026-6324: Libsoup: libsoup: http request smuggling via unsigned to signed conversion error

Status: published. Published: 2026-05-29. Updated: 2026-11-03.

A flaw was found in libsoup. A remote attacker could exploit an unsigned to signed conversion error in the `soup_body_input_stream_read_chunked()` function by sending a malicious HTTP request. This vulnerability occurs when libsoup operates behind a non-libsoup proxy server or as a proxy in front of a non-libsoup backend server. Successful exploitation can allow an attacker to bypass security controls, poison web caches, or gain unauthorized access.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Red Hat / Red Hat Enterprise Linux 10 (libsoup3): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (libsoup): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (libsoup): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (libsoup): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (libsoup): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 4.8 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.87% as of 2026-11-02; percentile 58.90%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-444

## Exploit evidence

- exploit: https://gitlab.gnome.org/GNOME/libsoup/-/work_items/508 (ADP: CISA-ADP)

## References

- https://access.redhat.com/security/cve/CVE-2026-6324 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2458479 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://gitlab.gnome.org/GNOME/libsoup/-/commit/96ac392b444d01bd5de1d1276b187c3ed49d048c (CNA: redhat)

- https://gitlab.gnome.org/GNOME/libsoup/-/issues/508 (CNA: redhat)

- https://gitlab.gnome.org/GNOME/libsoup/-/work_items/508 (ADP: CISA-ADP; exploit)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-6324; retrieved 2026-11-03; source updated 2026-11-03

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-6324; retrieved 2026-11-03; source updated Not reported

Revision: cddfa8f79d5deae3dfb28deb25c596a67249fe683f499243d5a8c1d11fbd8856

Canonical: https://y2.dev/cve/CVE-2026-6324

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