AuthPoint Authentication Gateway: Authentication Bypass by Capture-replay
CVE-2026-121640 is a critical-severity authentication bypass by capture-replay vulnerability in AuthPoint Authentication Gateway from WatchGuard, with a CVSS 4.0 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 7.6.0 as the first without the flaw, so updating AuthPoint Authentication Gateway to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.47% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update AuthPoint Authentication Gateway to 7.6.0 or a later version.
- Read the advisory on psirt.watchguard.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| WatchGuard | AuthPoint Authentication Gateway | 1.0 up to, but not including, 7.6.0 | 7.6.0 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Attack requirements
- PresentThe target must be in a specific state or configuration for the attack to work.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Confidentiality (vulnerable system)
- NoneNo loss of confidentiality on the vulnerable system.
- Integrity (vulnerable system)
- HighSerious loss of integrity on the vulnerable system.
- Availability (vulnerable system)
- HighSerious loss of availability on the vulnerable system.
- Confidentiality (other systems)
- NoneNo loss of confidentiality on systems beyond the vulnerable one.
- Integrity (other systems)
- HighSerious loss of integrity on systems beyond the vulnerable one.
- Availability (other systems)
- HighSerious loss of availability on systems beyond the vulnerable one.
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:H/SA:H/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. Scored by CNA.
Official description
An Authentication Bypass by Capture-replay vulnerability in WatchGuard AuthPoint Gateway allows an attacker who has observed a legitimate request between AuthPoint Gateway components to replay it and perform unauthorized administrative actions, including disrupting authentication services.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Authentication Bypass by Capture-replay
A capture-replay flaw exists when the design of the product makes it possible for a malicious user to sniff network traffic and bypass authentication by replaying it to the server in question to the same effect as the original message (or with minor changes).
How developers prevent this class of flaw
- Utilize some sequence or time stamping functionality along with a checksum which takes this into account in order to ensure that messages can be parsed only once.
- Since any attacker who can listen to traffic can see sequence numbers, it is necessary to sign messages with some kind of cryptography to ensure that sequence numbers are not simply doctored along with content.
More Authentication Bypass by Capture-replay vulnerabilities (CWE-294)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other vulnerabilities in AuthPoint Authentication Gateway
- 9.2 Critical severity
- 9.1 Critical severity
- 8.9 High severity
- 7.5 High severity
Recent Authentication Bypass by Capture-replay vulnerabilities
- 9.1 Critical severity
- 7.4 High severity
- 7.6 High severity
- 7.5 High severity
- 8.8 High severity
- 7.4 High severity
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