# CVE-2026-15711: Libsoup: soupwebsocketconnection: libsoup: websocket remote denial of service via oversized control frame protocol violation Status: published. Published: 2026-07-14. Updated: 2026-11-05. A vulnerability was found in libsoup's WebSocket frame parsing implementation. The library fails to validate length rules specified in RFC 6455 §5.5, which mandates that all WebSocket control frames (e.g., PING, PONG, CLOSE) contain a payload of 125 bytes or less. A remote, unauthenticated attacker can exploit this by sending a non-compliant, oversized control frame. Because the parser handles this protocol violation improperly instead of throwing an immediate connection termination error, it triggers a internal processing crash, resulting in a remote denial of service (DoS) for applications utilizing libsoup WebSockets. ## Remediation - workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. (source: CNA: redhat) ## Affected products and versions - Red Hat / Red Hat Enterprise Linux 10 (libsoup3): ≥ 0:3.6.5-3.el10_2.14; < * (unaffected, rpm). Source: CNA: redhat - Red Hat / Red Hat Enterprise Linux 10.0 Extended Update Support (libsoup3): ≥ 0:3.6.5-3.el10_0.17; < * (unaffected, rpm). Source: CNA: redhat - Red Hat / Red Hat Enterprise Linux 8 (libsoup): ≥ 0:2.62.3-15.el8_10; < * (unaffected, rpm). Source: CNA: redhat - Red Hat / Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support (libsoup): ≥ 0:2.62.3-2.el8_4.10; < * (unaffected, rpm). Source: CNA: redhat - Red Hat / Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On (libsoup): ≥ 0:2.62.3-2.el8_4.10; < * (unaffected, rpm). Source: CNA: redhat - Red Hat / Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support (libsoup): ≥ 0:2.62.3-2.el8_6.10; < * (unaffected, rpm). Source: CNA: redhat - Red Hat / Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On (libsoup): ≥ 0:2.62.3-2.el8_6.10; < * (unaffected, rpm). Source: CNA: redhat - Red Hat / Red Hat Enterprise Linux 8.8 Telecommunications Update Service (libsoup): ≥ 0:2.62.3-3.el8_8.11; < * (unaffected, rpm). Source: CNA: redhat - Red Hat / Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions (libsoup): ≥ 0:2.62.3-3.el8_8.11; < * (unaffected, rpm). Source: CNA: redhat - Red Hat / Red Hat Enterprise Linux 9 (libsoup): ≥ 0:2.72.0-16.el9_8.3; < * (unaffected, rpm). Source: CNA: redhat - Red Hat / Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions (libsoup): ≥ 0:2.72.0-8.el9_2.13; < * (unaffected, rpm). Source: CNA: redhat - Red Hat / Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions (libsoup): ≥ 0:2.72.0-8.el9_4.12; < * (unaffected, rpm). Source: CNA: redhat - Red Hat / Red Hat Enterprise Linux 9.6 Extended Update Support (libsoup): ≥ 0:2.72.0-10.el9_6.9; < * (unaffected, rpm). 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 ## Severity and prioritization - CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: CNA: redhat - CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: NVD: secalert@redhat.com - CISA KEV: No listing in collected sources - EPSS: 0.74% as of 2026-11-05; percentile 54.95% - SSVC: exploitation poc; automatable yes; technical impact partial; source ADP: CISA-ADP - Weaknesses: CWE-770 ## Exploit evidence - exploit: https://gitlab.gnome.org/GNOME/libsoup/-/issues/515 (ADP: CISA-ADP) ## References - https://access.redhat.com/errata/RHSA-2026:68234 (CNA: redhat; vendor-advisory, x_refsource_REDHAT) - https://access.redhat.com/errata/RHSA-2026:68235 (CNA: redhat; vendor-advisory, x_refsource_REDHAT) - https://access.redhat.com/errata/RHSA-2026:68266 (CNA: redhat; vendor-advisory, x_refsource_REDHAT) - https://access.redhat.com/errata/RHSA-2026:68612 (CNA: redhat; vendor-advisory, x_refsource_REDHAT) - https://access.redhat.com/errata/RHSA-2026:69108 (CNA: redhat; vendor-advisory, x_refsource_REDHAT) - https://access.redhat.com/errata/RHSA-2026:69297 (CNA: redhat; vendor-advisory, x_refsource_REDHAT) - https://access.redhat.com/errata/RHSA-2026:69863 (CNA: redhat; vendor-advisory, x_refsource_REDHAT) - https://access.redhat.com/errata/RHSA-2026:70598 (CNA: redhat; vendor-advisory, x_refsource_REDHAT) - https://access.redhat.com/errata/RHSA-2026:70599 (CNA: redhat; vendor-advisory, x_refsource_REDHAT) - https://access.redhat.com/errata/RHSA-2026:71389 (CNA: redhat; vendor-advisory, x_refsource_REDHAT) - https://access.redhat.com/security/cve/CVE-2026-15711 (CNA: redhat; vdb-entry, x_refsource_REDHAT) - https://bugzilla.redhat.com/show_bug.cgi?id=2499924 (CNA: redhat; issue-tracking, x_refsource_REDHAT) - https://gitlab.gnome.org/GNOME/libsoup/-/issues/515 (CNA: redhat) - https://gitlab.gnome.org/GNOME/libsoup/-/issues/515 (ADP: CISA-ADP; exploit) - https://access.redhat.com/errata/RHSA-2026:68234 (secalert@redhat.com) - https://access.redhat.com/errata/RHSA-2026:68235 (secalert@redhat.com) - https://access.redhat.com/errata/RHSA-2026:68266 (secalert@redhat.com) - https://access.redhat.com/errata/RHSA-2026:68612 (secalert@redhat.com) - https://access.redhat.com/errata/RHSA-2026:69108 (secalert@redhat.com) - https://access.redhat.com/errata/RHSA-2026:69297 (secalert@redhat.com) - https://access.redhat.com/errata/RHSA-2026:69863 (secalert@redhat.com) - https://access.redhat.com/errata/RHSA-2026:70598 (secalert@redhat.com) - https://access.redhat.com/errata/RHSA-2026:70599 (secalert@redhat.com) - https://access.redhat.com/errata/RHSA-2026:71389 (secalert@redhat.com) - https://access.redhat.com/security/cve/CVE-2026-15711 (secalert@redhat.com) - https://bugzilla.redhat.com/show_bug.cgi?id=2499924 (secalert@redhat.com) - https://gitlab.gnome.org/GNOME/libsoup/-/issues/515 (secalert@redhat.com) - https://gitlab.gnome.org/GNOME/libsoup/-/issues/515 (134c704f-9b21-4f2e-91b3-4a467353bcc0) ## Provenance - CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-15711; retrieved 2026-11-05; source updated 2026-11-05 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-15711; retrieved 2026-11-05; source updated 2026-11-05 - FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-15711; retrieved 2026-11-05; source updated Not reported Revision: 0fab8763d67833bfbc692360882870e978e20d0712141c6ddd588207d356fdae Canonical: https://y2.dev/cve/CVE-2026-15711 ## Agent and API access Public CVE pages, Markdown, and JSON are free to read without an account or API key. - Public catalog: https://y2.dev/cve/index.json. 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