CVE-2026-81433: Fireware OS Pre-Authentication Stack Buffer Overflow in fingerd Allows Remote Code Execution
Deferred
Published 29-09-2026Last modified 01-10-2026
Vulnerability summary
CVE-2026-81433 is a high (CVSS 8.7) Classic Buffer Overflow vulnerability in watchguard fireware os. EPSS estimates a 0.20% chance of exploitation in the next 30 days, higher than 9.3% of scored vulnerabilities.
CVSS score
8.7/10
010
High · v4.0 (CVE.org)EPSS score
0.20%
0%100%
Low · Change unavailableKEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded
Timeline
- 29-09-2026PublishedVulnerability first disclosed.
- 01-10-2026Last modifiedVulnerability information updated.
Description
A stack-based buffer overflow vulnerability in WatchGuard Fireware OS's DHCP fingerprinting daemon (fingerd) allows an unauthenticated attacker with adjacent network access to execute arbitrary code or crash the process by sending a specially crafted DHCP packet.
CVSS metrics
2 scores · 2 sources · 1 versionHigh 8.7Preferred score · CVE.org (CNA)
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NSourcesAll 2 agree
- NVDNIST8.7HighCVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/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
EPSS trend
Probability
0.20%
Chance of exploitation in the next 30 days
Percentile
9%
Versus all other CVEs
30-day change
Change unavailable
Change unavailable
30-09-202622-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.
- CWE-121Stack-based Buffer OverflowA stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
- CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.
Affected systems
Watchguard1 product
- fireware os≥ 2026.3, < 2026.3.2 | ≥ 2025.0, < 2026.2.3 | ≥ 12.0, < 12.12.3
1 vendor · 1 product
References
1 links- psirt.watchguard.com/CVE-2026-81433Vendor Advisory