CVE-2026-25529
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 · uneditedPostal is an open source SMTP server. Postal versions less than 3.3.5 had a HTML injection vulnerability that allowed unescaped data to be included in the admin interface. The primary way for unescaped data to be added is via the API's "send/raw" method. This could allow arbitrary HTML to be injected in to the page which may modify the page in a misleading way or allow for unauthorised javascript to be executed. Fixed in 3.3.5 and higher.
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 · high confidenceHTML injection vulnerability in Postal SMTP server versions before 3.3.5 allows unescaped user-controlled data from the 'send/raw' API endpoint to be rendered in the admin interface without proper output encoding, enabling arbitrary HTML or JavaScript injection.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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< 3.3.5CVSS 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
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify Postal server installationLocate the Postal server installation directory or check running processes. Common paths include /opt/postal or check for 'postal' process via 'ps aux | grep postal'. Determine the installation method (Docker, apt, or source) and locate the version file or command.Affected if Cannot determine version or Postal is not installed
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Determine installed Postal versionRun 'postal version' from the command line, or check the version file in the installation directory (often in a VERSION file or package.json). For Docker installations, check the image tag or inspect the container.Affected if Version cannot be determined or version is not < 3.3.5
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Verify send/raw API endpoint accessibilityCheck if the Postal API is accessible by attempting a request to the /api/v1/send/raw endpoint (port 5000 by default). This requires valid API credentials configured in Postal.Affected if API endpoint is not accessible or does not exist
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Confirm admin interface is accessibleVerify the Postal admin web interface is accessible (typically on port 5000 or 443). The vulnerability manifests when data from send/raw is rendered in the admin dashboard.Affected if Admin interface is not accessible or not in use
If the installed Postal version is below 3.3.5 and the admin interface is in use, the environment is affected by this HTML injection vulnerability.
Generated from the published advisory. Verify against your own configuration.
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 · scoped3.3.5
Upgrade to Postal version 3.3.5 or higher which implements proper output escaping for data rendered in the admin interface.
3.3.5
- Backup your current Postal installation and database before upgrading
- Check your current Postal version to confirm it is below 3.3.5
- Upgrade Postal to version 3.3.5 or higher using your deployment method (e.g., package manager, Docker, or source)
- After upgrading, verify that the 'send/raw' API endpoint now properly escapes HTML content before rendering in the admin interface
- Confirm the admin interface loads correctly and no XSS payload from previously injected data is executable
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation3.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-25529 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-25529 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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