7.1High
CVE-2025-71403
better-auth versions before 1.1.20 contain a bypass vulnerability in trustedOrigins validation logic affecting absolute URLs and wildcard domains. Attackers can construct malicious callbackURL parameters that pass origin checks and trigger open redirects to steal sensitive tokens for account takeover.
What this means for your business
- An attacker can use it remotely, over a network, without a login, but only after tricking someone into an action such as opening a file or a link.
- FIRST's prediction model gives it a 0.2% chance of attack attempts being seen in the next 30 days, ranking above 15% of all known flaws.
What to do
- 1Ask your IT team or provider whether any of your systems use the affected product.
- 2If you do, follow the vendor's guidance. No patch reference has been published yet.
Not sure if your company is exposed?
Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.
Scoring
- CVSS
- 7.1 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:N- CVSS v4
- 7.1
- Weakness
- CWE-601
- Assigned by
- disclosure@vulncheck.com
Dates
- Published
- 2026-08-01
- Last modified
- 2026-09-08
- Sources
- NVD