Summary
Pusher Service Channel Authentication Bypass
The service offered by Pusher provides "private" channels with an authentication mechanism that restricts subscription access. The decision on allowing subscriptions to private channels is delegated to customers, who implement an authentication endpoint. End-users request a token from this endpoint to join a specific channel. The token is an HMAC signature of the end-user's connection ID (socket_id) and the desired channel.
The issue arises from a lack of validation in the libraries provided to customers. This vulnerability allows a malicious end-user to submit a malformed socket_id field, leading the customer to unknowingly sign a string. This signed string grants access to a different private channel than the one the end-user is ostensibly requesting. Consequently, a malicious end-user, with permission to subscribe to one private channel, can forge permission for any private channel owned by the same customer.
Additionally, the HTTP API is secured by requiring a signature with each request, generated by the customer's secret key. In specific cases, a malicious end-user may deceive a customer into signing a value for socket_id, effectively authenticating an API request to Pusher.
Impact
GHSA-7V7M-PCW5-H3CG has a CVSS score of 6.5 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.2.1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is GHSA-7V7M-PCW5-H3CG? GHSA-7V7M-PCW5-H3CG is a medium-severity security vulnerability in pusher/pusher-php-server (composer), affecting versions < 2.2.1. It is fixed in 2.2.1.
- How severe is GHSA-7V7M-PCW5-H3CG? GHSA-7V7M-PCW5-H3CG has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of pusher/pusher-php-server are affected by GHSA-7V7M-PCW5-H3CG? pusher/pusher-php-server (composer) versions < 2.2.1 is affected.
- Is there a fix for GHSA-7V7M-PCW5-H3CG? Yes. GHSA-7V7M-PCW5-H3CG is fixed in 2.2.1. Upgrade to this version or later.
- Is GHSA-7V7M-PCW5-H3CG exploitable, and should I be worried? Whether GHSA-7V7M-PCW5-H3CG is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-7V7M-PCW5-H3CG is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-7V7M-PCW5-H3CG? Upgrade
pusher/pusher-php-serverto 2.2.1 or later.