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DiscourseApplication

CVE-2026-53961

MEDIUM · 6.5 CVSS v3.1 Published 2026-07-09
Fix available
A fix is available. Upgrade to 2026.1.5 / 2026.4.2 or later.
See remediation →
74/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click Patch available 6 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
DiscourseApplication
Affected:>= 2026.1.0, < 2026.1.5>= 2026.4.0, < 2026.4.2>= 2026.5.0, < 2026.5.1= 2026.6.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2026.1.5 / 2026.4.2 / 2026.5.1 or later
Fixed in 2026.1.52026.4.22026.5.1
Vendor patch github.com →
Recommended fix High confidence

2026.6.0 (or 2026.5.1/2026.4.2/2026.1.5 depending on your release branch)

  1. Identify your current Discourse version by checking the /admin/about page in your Discourse admin panel
  2. Back up your Discourse database and any custom plugins/themes before upgrading
  3. Upgrade your Discourse instance to version 2026.6.0 (or the latest stable release that includes the fix: 2026.6.0, 2026.5.1, 2026.4.2, or 2026.1.5 depending on your branch)
  4. For Docker-based installations, run `./launcher rebuild app` after updating the version
  5. For source installations, run `git pull` and then restart the application
  6. Verify the upgrade was successful by checking the version at /admin/about
  7. Confirm the fix is applied by reviewing the commit at https://github.com/discourse/discourse/commit/3a3d315a85ef3c6aabfc7e7bb38702059784f06b
Caveat Standard Discourse upgrade risks apply - test in staging first; review plugin compatibility with the new version

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-53961 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data