CVE-2026-53961: Discourse: Forged AWS SNS bounce notifications can disable a targeted user's email (missing TopicArn binding)
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 Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
discourse/discourseto a version that resolves this vulnerability.Fixed in 2026.6.0 - Upgrade
Upgrade
discourse/discourseto a version that resolves this vulnerability.Fixed in 2026.5.1 - Upgrade
Upgrade
discourse/discourseto a version that resolves this vulnerability.Fixed in 2026.4.2 - Upgrade
Upgrade
discourse/discourseto a version that resolves this vulnerability.Fixed in 2026.1.5
Event History
Frequently Asked Questions
What is the severity of CVE-2026-53961?
The severity of CVE-2026-53961 is classified as medium with a score of 6.5.
What does CVE-2026-53961 affect?
CVE-2026-53961 affects the Discourse open-source discussion platform.
How can CVE-2026-53961 be exploited?
CVE-2026-53961 can be exploited through forged AWS SNS bounce notifications that disable a targeted user's email due to missing TopicArn binding.
How do I fix CVE-2026-53961?
To fix CVE-2026-53961, upgrade Discourse to version 2026.6.0 or later.
What is the impact of CVE-2026-53961 on users?
The impact of CVE-2026-53961 on users is that it can lead to the disabling of their email notifications.