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CVE-2026-13376· NVD / CVE Program· CNA WatchGuard

WatchGuard Firebox Stored Cross-Site-Scripting (XSS) Vulnerability in spamBlocker Module

Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in WatchGuard Fireware OS spamBlocker module allows Stored XSS. This vulnerability is an additional unmitigated attack path for CVE-2025-1071. This issue affects Fireware OS 12.0 up to and including 12.12, 12.5 up to and including 12.5.18, and 2025.1 up to and including 2026.2.

MediumCVSS 4.8 · v4.0—No exploit No fix recorded
Published
Jul 2, 2026
Updated
Aug 27, 2026
EPSS
0.3% · 18th percentile
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Report tools

JSON

Action score

19

Monitor

Low priority for now.

CVSS
19 / 40 · 4.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · WatchGuard
4.8
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Affected systems

VendorProduct
watchguardfireware
watchguardfirebox m270
watchguardfirebox m290
watchguardfirebox m370
watchguardfirebox m390
watchguardfirebox m440
watchguardfirebox m4600
watchguardfirebox m470
watchguardfirebox m4800
watchguardfirebox m5600
watchguardfirebox m570
watchguardfirebox m5800

and 27 more

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • watchguard fireware12.0 and later · before 12.12.1
  • watchguard fireware2025.1 and later · before 2026.2.1
  • watchguard fireware12.5 and later · up to 12.5.18 inclusive

Versions reported by the vendor

Affected version ranges reported by the assigning authority (WatchGuard). Independent of NVD's CPE analysis and usually ahead of it.

  • WatchGuard Fireware OS

    • 2025.1 and later · before 2026.2.1affected
    • 12.0 and later · before 12.12.1affected
    • 12.0 and later · before 12.11.9affected
    • 12.0 and later · before 12.5.19affected

Same product

watchguard: all records

Other highest-scoring records for the same primary product.

  • CVE-2025-9242WatchGuard Firebox iked Out of Bounds Write VulnerabilityKEV
    94Now
  • CVE-2022-26318On WatchGuard Firebox and XTM appliances, an unauthenticated user can execute arbitrary code, aka FBX-22786.KEV
    92Now
  • CVE-2025-14733WatchGuard Firebox iked Out of Bounds Write VulnerabilityKEV
    75This week
  • CVE-2022-23176WatchGuard Firebox and XTM appliances allow a remote attacker with unprivileged credentials to access the system with a privileged managemenKEV
    68This week
  • CVE-2013-6021Buffer overflow in WGagent in WatchGuard WSM and Fireware before 11.8 allows remote attackers to execute arbitrary code via a long sessionid
    41Plan
  • CVE-2022-31789An integer overflow in WatchGuard Firebox and XTM appliances allows an unauthenticated remote attacker to trigger a buffer overflow and pote
    40Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-3343121 days apartWatchGuard Firebox Reflected Cross-Site-Scripting (XSS) Vulnerability in Fireware Web UI
    20Monitor
  • CVE-2026-133730 days apartWatchGuard Firebox Stored Cross-Site-Scripting (XSS) Vulnerability in Tigerpaw Technology Integration Configuration
    19Monitor
  • CVE-2026-133740 days apartWatchGuard Firebox Stored Cross-Site-Scripting (XSS) Vulnerability in ConnectWise Technology Integration Configuration
    19Monitor
  • CVE-2026-133750 days apartWatchGuard Firebox Stored Cross-Site-Scripting (XSS) Vulnerability in Autotask Technology Integration Configuration
    19Monitor
  • CVE-2026-133770 days apartWatchGuard Firebox Stored Cross-Site-Scripting (XSS) Vulnerability in SIP Proxy Configuration
    19Monitor
  • CVE-2025-13938210 days apartWatchGuard Firebox Stored Cross-Site-Scripting (XSS) Vulnerability in Autotask Technology Integration Configuration
    19Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • Administrator privileges are required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
High
User interaction
P
Scope
X

Weakness class (CWE)

CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/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

nvd-secondary

Root cause

User content is inserted into the page as HTML. The browser interprets the content as code rather than data.

The bug in code

The whole CWE-79 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
commentEl.innerHTML = comment.body;

Fixed

ts
commentEl.textContent = comment.body;

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records