CVE-2026-55840 Scoold: Open Redirect in getBackToUrl() allows phishing via domain-prefix startsWith bypass
Attackers can redirect users to malicious sites after login via flawed URL validation, enabling phishing and credential theft in Scoold.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-55840?
CVE-2026-55840 is a medium-severity vulnerability in Erudika scoold, published on 15 Oct 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Scoold is a Q&A and a knowledge sharing platform for teams. Prior to 1.69.1, the getBackToUrl() method in src/main/java/com/erudika/scoold/utils/HttpUtils.java validates the backto and returnto parameters with Strings.CI.startsWith against the configured server URL. An attacker can supply an absolute URL whose hostname begins with the legitimate hostname, causing URI.resolve() to retain the attacker URL and the prefix check to accept it. A victim who follows the crafted sign-in link can be redirected to an attacker-controlled domain after authentication, enabling phishing and possible credential or token theft. This issue is fixed in version 1.69.1.
Weakness: CWE-601
Which versions are affected by CVE-2026-55840?
How do I fix CVE-2026-55840?
No fix has been published for CVE-2026-55840 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-55840 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55840 exists.
Sources
Also known as GHSA-85fm-6f2v-74pq.