Algernon: Auto-refresh SSE event server sets Access-Control-Allow-Origin: *

Summary The SSE event server's Access-Control-Allow-Origin response header was hardcoded to the wildcard regardless of the caller's Origin. Because EventSource does not preflight and does not send cookies, the wildcard is sufficient to let any third-party page the developer visits open a...

Algernon: Auto-refresh SSE event server binds to all interfaces by default on Linux/macOS

Summary The SSE event server bound to 0.0.0.0:5553 on Linux/macOS by default because the platform-dependent host default in engine/flags.go:39-46 set host = "" for non-Windows, and utils.JoinHostPort"", ":5553" resolves to ":5553" — a Go http.Server.Addr of ":5553" listens on every interface. On...

Insecure Default Initialization of Resource

Overview Affected versions of this package are vulnerable to Insecure Default Initialization of Resource in the GenFileChangeEvents handler. An attacker can obtain continuous access to sensitive file and directory information by connecting to the SSE endpoint without authentication. Remediation...

Algernon: Auto-refresh SSE event server binds to all interfaces with Access-Control-Allow-Origin: * and no authentication

Summary When auto-refresh is enabled, Algernon spins up an SSE handler that streams a data: line for every filesystem event under the watched directory. The handler performs no authentication of any kind — no shared token, no cookie check against the permissions2 userstate, no IP allow-list, no...

CVE-2026-43968

A flaw was found in cowlib. An Improper Neutralization of CRLF Sequences Carriage Return Line Feed Injection vulnerability allows a remote attacker to inject bare carriage return characters into Server-Sent Events SSE fields. This enables event splitting and injection of arbitrary event types and...

CR Injection in SSE Encoder Enables Event Splitting via cow_sse:event/1

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CVE-2026-44217

sse-channel is an SSE-implementation which can be used to any node.js http request/response stream. Prior to 4.0.1, implementations that allow user-provided values to be passed to event, retry or id fields are susceptible to event spoofing, where an attacker could inject arbitrary messages into t...

@samanhappy/mcphub: SSE Endpoint Accepts Arbitrary Username from URL Path Without Authentication, Enabling User Impersonation

Summary A critical identity spoofing vulnerability in MCPHub allows any unauthenticated user to impersonate any other user — including administrators — on SSE Server-Sent Events and MCP transport endpoints. The server accepts a username from the URL path parameter and creates an internal user...

GHSA-WF8Q-WVV8-P8JF @samanhappy/mcphub: SSE Endpoint Accepts Arbitrary Username from URL Path Without Authentication, Enabling User Impersonation

Summary A critical identity spoofing vulnerability in MCPHub allows any unauthenticated user to impersonate any other user — including administrators — on SSE Server-Sent Events and MCP transport endpoints. The server accepts a username from the URL path parameter and creates an internal user...

CVE-2026-44217

sse-channel is an SSE-implementation which can be used to any node.js http request/response stream. Prior to 4.0.1, implementations that allow user-provided values to be passed to event, retry or id fields are susceptible to event spoofing, where an attacker could inject arbitrary messages into t...

CVE-2026-44217 sse-channel: SSE Injection via unsanitized event fields

sse-channel is an SSE-implementation which can be used to any node.js http request/response stream. Prior to 4.0.1, implementations that allow user-provided values to be passed to event, retry or id fields are susceptible to event spoofing, where an attacker could inject arbitrary messages into t...

ninenines cowlib: Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability allows SSE event splitting and injection via unvalidated field values

Improper Neutralization of CRLF Sequences 'CRLF Injection' vulnerability in ninenines cowlib allows SSE event splitting and injection via unvalidated field values. cowsse:event/1 in cowlib guards the id and event fields against \n but not against bare \r, and the internal prefixlines/2 function...

GHSA-HV23-4QP7-8C8R ninenines cowlib: Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability allows SSE event splitting and injection via unvalidated field values

Improper Neutralization of CRLF Sequences 'CRLF Injection' vulnerability in ninenines cowlib allows SSE event splitting and injection via unvalidated field values. cowsse:event/1 in cowlib guards the id and event fields against \n but not against bare \r, and the internal prefixlines/2 function...

CVE-2026-43968

Improper Neutralization of CRLF Sequences 'CRLF Injection' vulnerability in ninenines cowlib allows SSE event splitting and injection via unvalidated field values. cowsse:event/1 in cowlib guards the id and event fields against \n but not against bare \r, and the internal prefixlines/2 function...

CVE-2026-43968

Improper Neutralization of CRLF Sequences 'CRLF Injection' vulnerability in ninenines cowlib allows SSE event splitting and injection via unvalidated field values. cowsse:event/1 in cowlib guards the id and event fields against \n but not against bare \r, and the internal prefixlines/2 function...

CVE-2026-43968

Improper Neutralization of CRLF Sequences 'CRLF Injection' vulnerability in ninenines cowlib allows SSE event splitting and injection via unvalidated field values. cowsse:event/1 in cowlib guards the id and event fields against \n but not against bare \r, and the internal prefixlines/2 function...

CVE-2026-43968

CVE-2026-43968 involves an CRLF injection in ninenines/cowlib, triggered by the SSE encoding path cow_sse:event/1. The root cause is improper neutralization of CRLF sequences: while id and event fields guard against \n, bare \r is not sanitized, and prefix_lines/2 used for data and comment fields...

CVE-2026-43968 CR Injection in SSE Encoder Enables Event Splitting via cow_sse:event/1

Improper Neutralization of CRLF Sequences 'CRLF Injection' vulnerability in ninenines cowlib allows SSE event splitting and injection via unvalidated field values. cowsse:event/1 in cowlib guards the id and event fields against \n but not against bare \r, and the internal prefixlines/2 function...

EEF-CVE-2026-43968 CR Injection in SSE Encoder Enables Event Splitting via cow_sse:event/1

Summary Improper Neutralization of CRLF Sequences 'CRLF Injection' vulnerability in ninenines cowlib allows SSE event splitting and injection via unvalidated field values. cow\sse:event/1 in cowlib guards the id and event fields against \n but not against bare \r, and the internal prefix\lines/2...

PT-2026-39726

Name of the Vulnerable Software and Affected Versions cowlib versions 2.6.0 and later Description Improper Neutralization of CRLF Sequences CRLF Injection allows SSE event splitting and injection through unvalidated field values. The cow sse:event/1 function guards the id and event fields against...