CVE-2026-13371: WatchGuard Fireware OS · Deserialization of Untrusted Data
Affects WatchGuard Fireware OSSource CVE Database V5
Not known to be exploited · CVSS 6.9 Medium : upgrade to 2026.2.1 or 12.12.1 when convenient.
Data as of 14 Nov 2026, 20:44 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 48% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 2026.2.1, 12.12.1, 12.11.9 +1
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 2 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 14 Nov 2026.
What to do
Upgrade Fireware to 2026.2.1 or 12.12.1 (OS); 12.11.9 (OS); 12.5.19 (OS).
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| WatchGuardFireware OS | Affected
| Fixed in
|
| WatchGuardFireware OS | Affected
| Fixed in
|
| WatchGuardFireware OS | Affected
| Fixed in
|
| WatchGuardFireware OS | Affected
| Fixed in
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AI-suggested
If you cannot patch yet, restrict administrator access to trusted personnel only and monitor for unusual activity related to the put_data endpoint. Avoid sending untrusted or malformed data to the management interface.
Description
An 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.