CVE-2026-53961

MEDIUM

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

Title source: cna
STIX 2.1

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.

References (9)

Core 9
Core References

Scores

CVSS v3 6.5
EPSS 0.0022
EPSS Percentile 12.6%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact partial

Details

CWE
CWE-345
Status published
Products (3)
discourse/discourse >= 2026.1.0-latest, < 2026.1.5
discourse/discourse >= 2026.4.0-latest, < 2026.4.2
discourse/discourse >= 2026.5.0-latest, < 2026.5.1
Published Jul 09, 2026
Tracked Since Jul 10, 2026