CVE-2026-53961
Discourse: Forged AWS SNS bounce notifications can disable a targeted user's email (missing TopicArn binding)
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Description
Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, the AWS SES bounce webhook at POST /webhooks/aws verified that SNS messages were signed by Amazon but did not bind them to trusted TopicArn values, allowing any AWS account holder to publish validly signed forged Bounce notifications that revoke a targeted user email. This issue is fixed in versions 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5.
Affected
Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.
Remediation
No guide yetNo remediation guidance has been written for this CVE yet. What the record does show:
Patch and advisory references
- https://github.com/discourse/discourse/security/advisories/GHSA-8f9m-v436-wr3x
- https://github.com/discourse/discourse/commit/3a3d315a85ef3c6aabfc7e7bb38702059784f06b
- https://github.com/discourse/discourse/commit/61f12e13aa1b760f81d5ff60f12e3a7e77434b94
- https://github.com/discourse/discourse/commit/958f0cd831d65a49ec75f05343ca2c167679f0ea
- https://github.com/discourse/discourse/commit/aea35190791261bab258ebab05da279e78cdd0e6
References (9)
SSVC — Action Prioritization
SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.
CVSS
- Attack Vector
- NETWORK
- Complexity
- LOW
- Privileges
- NONE
- User Interaction
- NONE
- Scope
- UNCHANGED
- Confidentiality
- NONE
- Integrity
- LOW
- Availability
- LOW
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