Pusher Service Channel Authentication Bypass

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

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 (socketid) 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 socketid 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…

Published by the source

20 May 2024, 17:49 UTC

Last modified by the source

20 May 2024, 17:49 UTC

Source last checked

26 Oct 2026, 14:24 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-7v7m-pcw5-h3cg

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# Patch Next advisory brief: GHSA-7v7m-pcw5-h3cg

Advisory: Pusher Service Channel Authentication Bypass
IDs: GHSA-7v7m-pcw5-h3cg
Record: https://patchnext.com/advisories/ghsa-7v7m-pcw5-h3cg (revision 1, source checked 26 Oct 2026, 14:24 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pusher/pusher-php-server 2.2.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist pusher/pusher-php-server: affected < 2.2.1; fixed in 2.2.1

## Suggested inspection (read-only)
- Packagist pusher/pusher-php-server: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on pusher/pusher-php-server.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-7v7m-pcw5-h3cg (GitHub-reviewed advisory GHSA-7v7m-pcw5-h3cg lists affected ranges: Packagist pusher/pusher-php-server >=0 <2.2.1)

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