23 Oct 2026 15:48:27 UTC
Http4s: WebSocket decoder accepts negative length, causing infinite decode loop
cve-program · CVE-2026-69210 · Published
CVE-2026-69210
Http4s: WebSocket decoder accepts negative length, causing infinite decode loop
CVSS 3.1 7.5 HIGHCheck source for fixed versionsKEV status unknown
cve-program · CVE-2026-69210
PublishedHttp4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, WebSocket FrameTranscoder.bodyLength rejects extended payload lengths above Integer.MAX_VALUE but permits negative 64-bit lengths. A remote client that completes a WebSocket handshake through an Ember server can send such a frame, causing the decoder to return an empty frame without advancing its input. The decode loop then runs indefinitely, pins a worker at full CPU, and grows an ArrayBuffer without bound, resulting in denial of service. This issue is fixed in versions 0.23.35 and 1.0.0-M47.
Read the publisher's advisoryAffected versions, risk and source history
Exploitation and risk
Source statusCISA KEV lists vulnerabilities known to be exploited. FIRST EPSS estimates the likelihood of exploitation in the next 30 days. An unavailable score does not mean zero risk.
Which CVEs have scores here?
This view includes predictions for CVE identifiers explicitly listed in public NuGet advisories. Microsoft release pages have their own prediction coverage. Check source status for the scope and latest checks.
No exploitation or prediction data is available here for these CVEs. This does not mean they are safe or unlikely to be exploited.
Risk history
Compare earlier KEV listings and daily EPSS scores. Advisory wording and affected versions have a separate history.
When does an EPSS score appear as a change?
A prediction change is reported when EPSS rises from below 10% to 10% or higher. Other daily score changes remain in this history.
Advisory history
1 saved versionsSee how the publisher's advisory changed over time. Each link opens the version saved at that time. The publisher's update date can differ from the date shown here.
How advisory history works
Each link identifies one complete publisher record. History can include advisories that previously shared an identifier; an identifier removed by a publisher no longer establishes a current relationship. A historical link shows only that record and earlier saved versions. Failed checks and unchanged reads do not create new versions.