CVE-2026-53961
Discourse: Forged AWS SNS bounce notifications can disable a targeted user's email (missing TopicArn binding)
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.
INFO
Published Date :
July 9, 2026, 10:17 p.m.
Last Modified :
July 14, 2026, 8:37 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update Discourse to version 2026.6.0 or later.
- Verify webhook signature validation is correctly configured.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-53961.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-53961 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-53961
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-53961 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-53961 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Jul. 14, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:* versions from (including) 2026.1.0 up to (excluding) 2026.1.5 *cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:* versions from (including) 2026.4.0 up to (excluding) 2026.4.2 *cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:* versions from (including) 2026.5.0 up to (excluding) 2026.5.1 *cpe:2.3:a:discourse:discourse:2026.6.0:*:*:*:latest:*:*:* Added Reference Type GitHub, Inc.: https://github.com/discourse/discourse/commit/3a3d315a85ef3c6aabfc7e7bb38702059784f06b Types: Patch Added Reference Type GitHub, Inc.: https://github.com/discourse/discourse/commit/61f12e13aa1b760f81d5ff60f12e3a7e77434b94 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/discourse/discourse/commit/958f0cd831d65a49ec75f05343ca2c167679f0ea Types: Patch Added Reference Type GitHub, Inc.: https://github.com/discourse/discourse/commit/aea35190791261bab258ebab05da279e78cdd0e6 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/discourse/discourse/releases/tag/v2026.1.5 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/discourse/discourse/releases/tag/v2026.4.2 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/discourse/discourse/releases/tag/v2026.5.1 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/discourse/discourse/releases/tag/v2026.6.0 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/discourse/discourse/security/advisories/GHSA-8f9m-v436-wr3x Types: Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 10, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-53961', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-10T13:44:24.781167Z'} -
New CVE Received by [email protected]
Jul. 09, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'discourse', 'product': 'discourse', 'versions': [{'status': 'affected', 'version': '>= 2026.5.0-latest, < 2026.5.1'}, {'status': 'affected', 'version': '>= 2026.4.0-latest, < 2026.4.2'}, {'status': 'affected', 'version': '>= 2026.1.0-latest, < 2026.1.5'}]}] Added 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L Added CWE CWE-345 Added Reference https://github.com/discourse/discourse/commit/3a3d315a85ef3c6aabfc7e7bb38702059784f06b Added Reference https://github.com/discourse/discourse/commit/61f12e13aa1b760f81d5ff60f12e3a7e77434b94 Added Reference https://github.com/discourse/discourse/commit/958f0cd831d65a49ec75f05343ca2c167679f0ea Added Reference https://github.com/discourse/discourse/commit/aea35190791261bab258ebab05da279e78cdd0e6 Added Reference https://github.com/discourse/discourse/releases/tag/v2026.1.5 Added Reference https://github.com/discourse/discourse/releases/tag/v2026.4.2 Added Reference https://github.com/discourse/discourse/releases/tag/v2026.5.1 Added Reference https://github.com/discourse/discourse/releases/tag/v2026.6.0 Added Reference https://github.com/discourse/discourse/security/advisories/GHSA-8f9m-v436-wr3x