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Vulnerability · Published Jul 9, 2026 · Assigned by GitHub_M

CVE-2026-53961Discourse: Forged AWS SNS bounce notifications can disable a targeted user's email (missing TopicArn binding)

Medium 6.5

In plain English

A medium-severity insufficient verification of data authenticity in discourse from discourse. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 23% of all known vulnerabilities).

Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.3%top 77.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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 products (as reported)

VendorProductVersions
discourse discourse >= 2026.5.0-latest, < 2026.5.1>= 2026.4.0-latest, < 2026.4.2>= 2026.1.0-latest, < 2026.1.5

Weakness: CWE-345 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

References