CVE-2026-15711
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidencelibsoup's WebSocket implementation fails to enforce RFC 6455 §5.5, which requires control frames (PING, PONG, CLOSE) to have payloads of 125 bytes or less. When a remote attacker sends oversized control frames, the parser improperly handles the protocol violation instead of terminating the connection, causing an internal crash and DoS.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Check if libsoup is installedQuery your system's package manager for libsoup (e.g., dpkg -l | grep libsoup, rpm -qa | grep libsoup, or apk list installed | grep libsoup) or scan for the libsoup shared library files (e.g., find /usr/lib -name 'libsoup*.so*' 2>/dev/null)Affected if libsoup is not present on the system, then the vulnerability does not apply
-
Identify the installed libsoup versionRun the appropriate package query to retrieve the version number (e.g., pkg-config --modversion libsoup-2.4, or dpkg -l libsoup-2.4, or rpm -q libsoup-2.4)Affected if the installed version is unknown or older than the version that includes the RFC 6455 validation fix
-
Verify if WebSocket functionality is in useInspect application logs, configuration files, or source code that uses libsoup to determine if WebSocket connections (SOUP_WEBSOCKET) are being created or accepted; also check for any WebSocket server endpoints or client connectionsAffected if the application does not use WebSocket features at all, then the malformed control frame attack surface does not exist
You are affected if you have a vulnerable version of libsoup installed AND your application actively uses libsoup WebSocket connections that can receive frames from remote attackers.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUpdate libsoup to a version that includes proper RFC-compliant validation of WebSocket control frame lengths, or apply vendor-provided patches.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-15711 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-15711 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data