CVE-2026-62317 Logto: ReDoS via unescaped user input in email subaddressing regex (blockSubaddressing)
Attackers can cause denial of service in Logto authentication services by triggering catastrophic backtracking in email validation regex when subaddressing blocking is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-62317?
CVE-2026-62317 is a high-severity denial of service vulnerability in logto-io logto, published on 19 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Logto is the modern, open-source auth infrastructure for SaaS and AI apps. Prior to 1.41.0, Logto's email subaddressing blocklist in packages/core/src/libraries/sign-in-experience/email-blocklist-policy.ts used the attacker-controlled domain from email input to construct subaddressingRegex when blockSubaddressing was enabled. The permissive emailRegEx accepted multiple at signs and regular expression metacharacters, and POST /api/experience/verification/verification-code could therefore cause catastrophic backtracking in subaddressingRegex.test(email). The resulting event-loop stall could make authentication, token issuance, SSO, and the administrative console unavailable. This issue is fixed in version 1.41.0.
Weakness: CWE-1333
Which versions are affected by CVE-2026-62317?
How do I fix CVE-2026-62317?
No fix has been published for CVE-2026-62317 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-62317 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-62317 exists.
Sources
Also known as GHSA-qp7j-c3q2-g739.