What is CVE-2026-13371?

CVE-2026-13371 is a medium-severity vulnerability in Watchguard Firebox Cloud, classified under Deserialization of Untrusted Data. CVSS score: 4.9/10. Published 2026-07-03.

How severe is CVE-2026-13371?

Medium severity. CVSS v3 base score is 4.9 out of 10.

Deserialization in Watchguard Firebox Cloud

CVE-2026-13371

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.

Vulnerability class: Insecure Deserialization

Published 2026-07-03 · last modified 2026-08-28.

CVSS v3 metric

CVSS v3 base score 4.9 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.006 (46.2th percentile), scored 2026-10-05.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 46.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.006 · change: +0.002

Affected products

Weakness classification (CWE)

CWE-502 — Deserialization of Untrusted Data

References

5d1c2695-1a31-4499-88ae-e847036fd7e3 (vendor-advisory, Vendor Advisory)
5d1c2695-1a31-4499-88ae-e847036fd7e3 (vendor-advisory, Broken Link)

Frequently asked questions

What is CVE-2026-13371?: CVE-2026-13371 is a medium-severity vulnerability in Watchguard Firebox Cloud, classified under Deserialization of Untrusted Data. CVSS score: 4.9/10. Published 2026-07-03.
How severe is CVE-2026-13371?: Medium severity. CVSS v3 base score is 4.9 out of 10.