CyberSecBulletin
CVE-2026-40905NVD status: Deferred

LinkAce: URL Redirection to Untrusted Site

Published Updated By the CyberSecBulletin desk

CVE-2026-40905 is a high-severity URL redirection to untrusted site vulnerability in LinkAce from Kovah, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. Affected LinkAce versions: < 2.5.4. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.29% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of LinkAce you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on github.com for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
  4. Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.

Affected products and versions

VendorProductAffected versionsFixed in
KovahLinkAce< 2.5.4Not 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
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
RequiredA user must take an action such as opening a file or link.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
NoneAvailability is not affected.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N. Scored by CNA (github.com).

Official description

LinkAce is a self-hosted archive to collect website links. Prior to 2.5.4, a password reset poisoning vulnerability was identified in the application due to improper trust of user-controlled HTTP headers. The application uses the X-Forwarded-Host header when generating password reset URLs. By manipulating this header during a password reset request, an attacker can inject an attacker-controlled domain into the reset link sent via email. As a result, the victim receives a password reset email containing a malicious link pointing to an attacker-controlled domain. When the victim clicks the link, the password reset token is transmitted to the attacker-controlled server. An attacker can capture this token and use it to reset the victim’s password, leading to full account takeover. This vulnerability is fixed in 2.5.4.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: URL Redirection to Untrusted Site

The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.

How developers prevent this class of flaw

  • Use an intermediate disclaimer page that provides the user with a clear warning that they are leaving the current site. Implement a long timeout before the redirect occurs, or force the user to click on the link. Be careful to avoid XSS problems (CWE-79) when generating the disclaimer page.
  • When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs. For example, ID 1 could map to /login.asp and ID 2 could map to http://www.example.com/. Features such as the ESAPI AccessReferenceMap provide this capability.
  • Ensure that no externally-supplied requests are honored by requiring that all redirect requests include a unique nonce generated by the application. Be sure that the nonce is not predictable (CWE-330).

More URL Redirection to Untrusted Site vulnerabilities (CWE-601)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in LinkAce

All LinkAce vulnerabilities

Recent URL Redirection to Untrusted Site vulnerabilities

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