CVE-2026-13371
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 · uneditedAn authenticated administrator can trigger a denial-of-service condition in the Fireware Management Web UI by sending malformed or crafted data to the put_data endpoint, which performs unsafe deserialization of the attacker-supplied input.
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 · moderate confidenceThe vulnerability exists in the Fireware Management Web UI's put_data endpoint, which performs unsafe deserialization of attacker-supplied input. An authenticated administrator can send malformed or crafted data to trigger this condition, leading to a denial-of-service state.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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
- High
- Authentication
- X
- User interaction
- None
- Scope
- X
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
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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Confirm Fireware Management Web UI is accessibleAttempt to access the Fireware Management Web UI login page (typically https://<device-ip>/sslvpn.html or /ssg/soswebui.htm). Verify the service is reachable and responds.Affected if The Web UI is exposed and accessible on the network.
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Identify the WatchGuard Fireware versionLog into the Web UI and navigate to System > Status or About, or use the CLI command 'fwsm -v' or 'fireware -v' to retrieve the installed Fireware OS version number.Affected if No patch is available and the version cannot be determined or is older than the vendor's patched release.
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Verify the put_data endpoint is availableAccess the Web UI as an administrator and inspect network traffic or check for the presence of endpoints under /ssg/ or /api/ that handle data submission, specifically looking for put_data or similar named handlers.Affected if The put_data endpoint exists and accepts unauthenticated or weakly authenticated input.
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Review authentication enforcement on the endpointExamine the Web UI configuration or proxy settings to confirm whether the put_data endpoint enforces proper admin authentication and session validation.Affected if The endpoint can be reached without full admin authentication or accepts data without validation.
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Check for denial-of-service indicators in logsReview system logs, Web UI access logs, or watchdog logs for crashes, restarts, or error messages related to the put_data endpoint or deserialization failures.Affected if Recent logs show crashes, service restarts, or deserialization errors following admin activity.
A user is affected if they have the Fireware Management Web UI exposed, the put_data endpoint is accessible, and the Fireware version is unpatched against this unsafe deserialization flaw.
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.
From vendor dataApply vendor patches when available; until then, restrict administrative access to the Fireware Management Web UI to trusted personnel only and monitor for abuse of the put_data endpoint.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-13371 — 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-2026-13371 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
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