CVE-2026-53961 json
Discourse: Forged AWS SNS bounce notifications can disable a targeted user's email (missing TopicArn binding)
published 4mo ago modified 2mo ago also BIT-discourse-2026-53961 , EUVD-2026-42728 , GHSA-8f9m-v436-wr3x
- cvss
- 6.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 22%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- bitnami discourse 2026.1.5, 2026.4.2, 2026.5.1
- discourse discourse 2026.1.5, 2026.4.2, 2026.5.1
- github.com/discourse/discourse@3a3d315 commit
- github.com/discourse/discourse@61f12e1 commit
- github.com/discourse/discourse@958f0cd commit
- github.com/discourse/discourse@aea3519 commit
- github.com/discourse/discourse/releases/tag/v2026.1.5 release
- github.com/discourse/discourse/releases/tag/v2026.4.2 release
- github.com/discourse/discourse/releases/tag/v2026.5.1 release
- github.com/discourse/discourse/releases/tag/v2026.6.0 release
Is CVE-2026-53961 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 4mo ago
Exploit prediction
0.30% chance of exploitation in the next 30 days, higher than 22% of all scored CVEs (FIRST EPSS, 2026-11-11).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L |
| OSV | 3.1 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| bitnami | discourse | >=2026.1.0, <2026.1.5 >=2026.4.0, <2026.4.2 >=2026.5.0, <2026.5.1 |
2026.1.5 2026.4.2 2026.5.1 |
Affected products
- discourse discourse
Classification
- Weakness
-
- CWE-345 Insufficient Verification of Data Authenticity
References
-
github.com
/discourse/discourse/commit/3a3d315a85ef3c6aabfc7e7bb38702059784f06b
patch
-
github.com
/discourse/discourse/commit/61f12e13aa1b760f81d5ff60f12e3a7e77434b94
patch
-
github.com
/discourse/discourse/commit/958f0cd831d65a49ec75f05343ca2c167679f0ea
patch
-
github.com
/discourse/discourse/commit/aea35190791261bab258ebab05da279e78cdd0e6
patch
-
github.com
/discourse/discourse/security/advisories/GHSA-8f9m-v436-wr3x
vendor-advisory, advisory
-
github.com
/discourse/discourse/releases/tag/v2026.1.5
release-notes, article
-
github.com
/discourse/discourse/releases/tag/v2026.4.2
release-notes, article
-
github.com
/discourse/discourse/releases/tag/v2026.5.1
release-notes, article
-
github.com
/discourse/discourse/releases/tag/v2026.6.0
release-notes, article
-
nvd.nist.gov
/vuln/detail/CVE-2026-53961
web
Sources
- CVE List CVE-2026-53961
- NVD CVE-2026-53961
- OSV BIT-discourse-2026-53961
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.