# CVE-2026-15714: Libsoup: soupmultipartinputstream: libsoup: out-of-bounds read in soup_multipart_input_stream_read_headers via an oversized multipart boundary string

Status: published. Published: 2026-07-14. Updated: 2026-11-05.

An out-of-bounds read vulnerability was found in libsoup's multipart processing subsystem. The flaw exists in the soup_multipart_input_stream_read_headers() function inside soup-multipart-input-stream.c, which does not adequately restrict or validate the size of incoming multipart boundary strings. When processing a crafted HTTP response containing a malformed or oversized boundary parameter, the internal stream reader reads past the allocated buffer bounds. A remote, unauthenticated attacker can exploit this behavior to cause a service denial (DoS) through application failure or potentially read fragments of unauthorized memory metadata.

## Remediation

- workaround: To mitigate this issue, restrict network access to applications that utilize libsoup for processing multipart messages from untrusted sources. Implement firewall rules to limit incoming connections to only trusted clients, thereby reducing the attack surface. If the vulnerable component is part of a service, ensure that the service is not exposed to untrusted networks. (source: CNA: redhat)

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

- CVSS 3.1: 6.5 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L; source: NVD: secalert@redhat.com

- CISA KEV: No listing in collected sources

- EPSS: 0.39% as of 2026-11-05; percentile 33.35%

- SSVC: exploitation poc; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-125

## Exploit evidence

- exploit: https://gitlab.gnome.org/GNOME/libsoup/-/work_items/542 (ADP: CISA-ADP)

## References

- https://access.redhat.com/security/cve/CVE-2026-15714 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2499942 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://gitlab.gnome.org/GNOME/libsoup/-/work_items/542 (CNA: redhat)

- https://gitlab.gnome.org/GNOME/libsoup/-/work_items/542 (ADP: CISA-ADP; exploit)

- https://access.redhat.com/security/cve/CVE-2026-15714 (secalert@redhat.com)

- https://bugzilla.redhat.com/show_bug.cgi?id=2499942 (secalert@redhat.com)

- https://gitlab.gnome.org/GNOME/libsoup/-/work_items/542 (secalert@redhat.com)

- https://gitlab.gnome.org/GNOME/libsoup/-/work_items/542 (134c704f-9b21-4f2e-91b3-4a467353bcc0)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-15714; retrieved 2026-11-05; source updated 2026-11-05

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-15714; retrieved 2026-11-05; source updated 2026-11-05

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-15714; retrieved 2026-11-05; source updated Not reported

Revision: 1607b1dd71ff03330805595e1a5ca6da00d60efdf52f6701e33be2b3e2d3a9ed

Canonical: https://y2.dev/cve/CVE-2026-15714

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