CVE-2021-41163: RCE via malicious SNS subscription payload

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 19.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-10-20 · updated 2026-06-17
Weakness: CWE-74

Description

Discourse is an open source platform for community discussion. In affected versions maliciously crafted requests could lead to remote code execution. This resulted from a lack of validation in subscribe_url values. This issue is patched in the latest stable, beta and tests-passed versions of Discourse. To workaround the issue without updating, requests with a path starting /webhooks/aws path could be blocked at an upstream proxy.

Affected products

discourse: before 2.7.9; 2.8.0-beta1, 2.8.0-beta2, 2.8.0-beta3, 2.8.0-beta4, 2.8.0-beta5, 2.8.0-beta6 — fixed in 2.7.9

How to fix

Upgrade to a fixed version: discourse 2.7.9. Check the vendor advisory for mitigations.

References

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