CVE-2026-81851: Fireware OS Heap-Based Buffer Overflow in iked Allows Denial of Service
Deferred
Published 27-08-2026Last modified 28-08-2026
Vulnerability summary
CVE-2026-81851 is a medium (CVSS 6.9) Heap-based Buffer Overflow vulnerability in watchguard fireware os. EPSS estimates a 0.41% chance of exploitation in the next 30 days, higher than 33.8% of scored vulnerabilities.
CVSS score
6.9/10
010
Medium · v4.0 (CVE.org)EPSS score
0.41%
0%100%
Low · +0.16 pp in 30 daysKEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded
Timeline
- 27-08-2026PublishedVulnerability first disclosed.
- 28-08-2026Last modifiedVulnerability information updated.
Description
A heap-based buffer overflow vulnerability in Fireware OS's iked process allows an authenticated administrator to crash the IKE daemon (iked), resulting in a denial of service, by saving a specially crafted configuration.
CVSS metrics
2 scores · 2 sources · 1 versionMedium 6.9Preferred score · CVE.org (CNA)
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NSourcesAll 2 agree
- NVDNIST6.9MediumCVSS: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
EPSS trend
Probability
0.41%
Chance of exploitation in the next 30 days
Percentile
34%
Versus all other CVEs
30-day change
Increase +0.16 pp
From 0.25% on 22-09-2026
22-09-202622-10-2026
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-122Heap-based Buffer OverflowA heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
- CWE-1284Improper Validation of Specified Quantity in InputThe product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties.
Affected systems
Watchguard1 product
- fireware os≥ 2025.0, < 2026.2.1 | ≥ 12.0, < 12.12.1 | ≥ 12.0, < 12.11.9 | ≥ 12.0, < 12.5.18
1 vendor · 1 product
References
1 links- psirt.watchguard.com/CVE-2026-81851Vendor Advisory