CVE-2026-15711: Libsoup: soupwebsocketconnection: libsoup: websocket remote denial of service via oversized control frame protocol violation

highCVSS 7.5CVE-2026-15711

CSIRTS triage

vendor: libsoup product: libsoup Denial of service

What: There is a remote denial of service vulnerability via oversized control frame protocol violation.
Who is affected: Deployments of libsoup are affected.
Urgency: Remediation is urgent due to the high severity of the vulnerability.
Action: Upgrade to a patched version of libsoup.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: high — CVSS 7.5
Published: 2026-07-14
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-15711

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-157110.43% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 35% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-15711	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

highCVE-2026-15711: A vulnerability was found in libsoup's WebSocket frame parsing implementation. The library fai…nvd

Recent advisories for Libsoup

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

high[UPDATE] [hoch] Red Hat Enterprise Linux (SSSD, libsoup): Mehrere Schwachstellencert-bund · 2026-07-31
mediumCVE-2026-66339: A flaw was found in libsoup. After a CONNECT tunnel is established through an HTTP proxy, libs…nvd · 2026-07-24
mediumCVE-2026-66338: A flaw was found in libsoup. The chunked transfer encoding parser uses a permissive parsing fu…nvd · 2026-07-24
mediumCVE-2026-66337: A flaw was found in libsoup. An unsigned integer underflow in the soup_filter_input_stream_rea…nvd · 2026-07-24
mediumCVE-2026-12548: A heap out-of-bounds read flaw was found in libsoup. When parsing multipart HTTP messages, an …nvd · 2026-07-21
high[UPDATE] [high] Red Hat Enterprise Linux (libsoup): Vulnerability allows information disclosurecert-bund · 2026-07-17