CVE-2026-116127: critical vulnerability in Starlet
Starlet versions before 0.33 for Perl send a body in responses to HEAD requests, corrupting the next response on a persistent or pipelined connection
Published · Updated
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
28Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 9.1epss 0.2%
Starlet versions before 0.33 for Perl send a body in responses to HEAD requests, corrupting the next response on a persistent or pipelined connection.
The request method is not passed to the response writer, so whatever body the application returns for a HEAD request is sent. With Plack::Middleware::Head the body is empty, but an HTTP/1.1 response without a Content-Length header still gets the chunked encoding terminator. Responses with status 204 or 304 are also sent with their body.
Pipelined GET and HEAD requests keep the connection open even when keep-alive is disabled, which is the default. A client or proxy reading the connection takes the extra bytes as the start of the next response, which may desynchronize a proxy that shares the connection across clients.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Affected products
StarletRelated CVEs — Starlet
In the same product, most dangerous first.
CVE-2026-116128HIGHStarlet versions from 0.20 before 0.33 for Perl allow memory exhaustion via unbounded buffering when decoding chunked request bodiesEPSS 0.2%CVE-2026-115866HIGHStarlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodiesEPSS 0.2%CVE-2026-115865HIGHStarlet versions before 0.33 for Perl allow a request declaring a large Content-Length to kill a worker by exhausting memoryEPSS 0.2%