WatchGuard Firebox iked Out of Bounds Write Vulnerability

Primary CVSS: v4.0 9.3 CRITICAL from 5d1c2695-1a31-4499-88ae-e847036fd7e3

CVSS:4.0/AV:N/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:Red

EPSS: 0.265100000 probability, percentile 0.978560000 (date 2026-08-21)

CISA KEV: Listed on 2025-12-19; due 2025-12-26; ransomware use Unknown

Problem Types: CWE-787 | CWE-787 CWE-787

Discovery Credit

CNA: Discovered internally by WatchGuard (en)

Solutions

CNA: Fireware OS 2025.1.4, Fireware OS 12.11.6, Fireware OS 12.5.15, Fireware OS 12.3.1-b728352 In addition to installing the latest Fireware OS that contains the fix, administrators that have confirmed threat actor activity on their Firebox appliances must take precautions to rotate all locally stored secrets on vulnerable Firebox appliances as described in our Best Practices to Rotate Shared Secrets Stored on the Firebox knowledge base article (https://techsearch.watchguard.com/KB?type=Article&SFDCID=kA1Vr000000DNMzKAO&lang=en_US).

Workarounds

CNA: If your Firebox is only configured with Branch Office VPN tunnels to static gateway peers and you are not able to immediately upgrade the device to a version of Fireware OS with the vulnerability resolution, you can follow WatchGuard’s recommendations for Secure Access to Branch Office VPNs that Use IPSec and IKEv2 (https://techsearch.watchguard.com/KB?type=Article&SFDCID=kA1Vr000000DMXNKA4&lang=en_US) as a temporary workaround.

Exploits

CNA: WatchGuard has observed threat actors actively attempting to exploit this vulnerability in the wild. Post-Exploit Activity We have identified two variants of post-exploit activity targeting exposed Firebox appliances. In one variant, the threat actor encrypts and then exfiltrates the active configuration file from the Firebox to the same IP address that the attack originates from. In the second variant, the threat actor creates a gzip archive with both the active configuration file and the local management user database and exfiltrates the archive to the same IP address that the attack originates from. In all instances where a successful exploit is suspected, Firebox administrators should follow the remediation guidance described below and rotate all secrets stored on the Firebox. Indicators of Attack We are providing the following Indicators of Attack (IoAs) to help device owners identify potential attempts to exploit this vulnerability against vulnerable Firebox appliances. These IoAs are only applicable on devices that lack the resolution described later in this advisory. IP Addresses The following IP addresses are directly associated with known threat actor activity. Outbound connections to these IPs are a strong indicator of compromise. Inbound connections from these IPs could indicate reconnaissance efforts or exploit attempts. - 45.95.19[.]50 - 51.15.17[.]89 - 172.93.107[.]67 - 199.247.7[.]82 - 38.252.8[.]14 - Added Dec 29 - 94.249.197[.]106 - Added Dec 29 Logs Invalid peer certificate chain With the iked diagnostic logging set to the default error logging level, the iked process generates a log message when the Firebox receives an IKE2 Auth payload with more than 8 certificates. This is a medium indicator of attack that the WatchGuard Threat Lab has observed associated with some threat actor activity. 1970-01-01 01:00:00 2025 Firebox-Name local3.err iked[2938]: (203.0.113.1<->203.0.113.2) Received peer certificate chain is longer than 8. Reject this certificate chain Abnormally large IKE_AUTH request CERT payload With the iked diagnostic logging set to the info logging level, the iked process generates a log message when the Firebox receives an IKE_AUTH request message. An IKE_AUTH request log message with an abnormally large CERT payload size (greater than 2000 bytes) is a strong indicator of an attack. This is a strong indicator of attack. 1970-01-01 01:00:00 iked (203.0.113.1<->203.0.113.2)"IKE_AUTH request" message has 6 payloads [ IDi(sz=21) CERT(sz=3000) SA(sz=44) TSi(sz=24) TSr(sz=24) N(sz=8)] Device Behavior IKE process hang During a successful exploit, the IKED process (responsible for handling IKE negotiations) will hang, interrupting VPN tunnel negotiations and re-keys. This is a strong indicator of attack. Existing tunnels may continue to pass traffic. IKE process crash After a failed or successful exploit, the IKED process will crash and generate a fault report on the Firebox. Be aware, there are other situations that could cause the IKED process to crash. This is a weak indicator of attack.