vulnerability-lookup: Authentication Bypass by Capture-replay
CVE-2026-73431 is a high-severity authentication bypass by capture-replay vulnerability in vulnerability-lookup, with a CVSS 4.0 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected vulnerability-lookup versions: 5.5.1 and earlier. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.35% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of vulnerability-lookup you run against the affected versions below, and install the vendor's latest release.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Vulnerability-lookup | vulnerability-lookup | 5.5.1 and earlier | Not stated |
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
- HighSuccess depends on conditions outside the attacker's control.
- Attack requirements
- NoneThe attack does not depend on a particular deployment or configuration.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Confidentiality (vulnerable system)
- HighSerious loss of confidentiality on the vulnerable system.
- Integrity (vulnerable system)
- HighSerious loss of integrity on the vulnerable system.
- Availability (vulnerable system)
- NoneNo loss of availability on the vulnerable system.
- Confidentiality (other systems)
- HighSerious 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)
- NoneNo loss of availability on systems beyond the vulnerable one.
Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/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. Scored by CNA.
Official description
Vulnerability-Lookup contains an authentication weakness in its account activation and password-recovery mechanism. Activation and recovery links were generated using stateless signed tokens containing only the user's login. Although the token signature and age were validated, the application did not track whether a token had already been successfully used. As a result, a captured activation or password-recovery link remained valid for the entire configured TOKEN_VALIDITY_PERIOD, even after the associated password had been changed. An attacker who obtains a valid activation or recovery token could therefore replay it multiple times during its validity period to set a new password and repeatedly take control of the affected account. In addition, tokens were not bound to a specific purpose, allowing the same token mechanism to be used across activation and recovery workflows. The patch introduces purpose-bound tokens and a random nonce whose SHA-256 digest is stored with the user account. The nonce is invalidated after a successful password change, making tokens single-use, while issuing a new token invalidates any previously issued token. The password-setting operation now explicitly consumes the token before committing the account change. Successful exploitation requires the attacker to obtain a currently valid activation or recovery link, but does not require knowledge of the victim's existing password or an authenticated session.
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: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Authentication Bypass by Capture-replay vulnerabilities
- 9.8 Critical severity
- 8.1 High severity
- 9.1 Critical severity
- 9.8 Critical severity
- 8.2 High severity
- 7.4 High severity
Spotted an error? Tell us.