CVE-2026-63405: AnyCable: Pusher REST API Does Not Verify Request Body MD5 Enabling Signed-Request Replay with Arbitrary Body

September 18, 2026

The Pusher-compatible REST API includes body_md5 in the HMAC signature string but never computes or verifies the MD5 of the received HTTP body, allowing anyone who observes a signed request to replay it with an entirely different body.

References

github.com/advisories/GHSA-5p54-whvp-x327
github.com/anycable/anycable/commit/d2cbadec792f038f4695c84a65c0d957b0fde72c
github.com/anycable/anycable/releases/tag/v1.6.15
github.com/anycable/anycable/security/advisories/GHSA-5p54-whvp-x327
nvd.nist.gov/vuln/detail/CVE-2026-63405

Code Behaviors & Features

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