Is CVE-2026-15617 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-15617 being exploited in the wild.

How severe is CVE-2026-15617?

Informational severity, published 23 July 2026.

Is there a fix for CVE-2026-15617?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-15617 attacked?

It is attacked over the network, in a hosted service.

Am I affected by CVE-2026-15617?

Check whether you run Logto at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-15617: Logto account takeover via improper identifier normalization

CVE-2026-15617 · Severity: info · Published 2026-07-23

Logto is an open-source identity infrastructure used to manage user authentication and sign-in experiences. A security flaw in how the system handles email addresses and identifiers allows attackers to potentially gain unauthorized access to accounts. By using variations of an email address (such as changing capitalization or using special Unicode characters), an attacker can cause the system to confuse two different identities, leading to account takeover or unauthorized access to sensitive user data.

Technologies: Logto. Vendors: Logto.

Quick answers

Is CVE-2026-15617 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-15617 being exploited in the wild.
How severe is CVE-2026-15617?: Informational severity, published 23 July 2026.
Which products and versions are affected?: Logto 1.10.1 to 1.37.1.
Is there a fix for CVE-2026-15617?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-15617 attacked?: It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-15617?: Check whether you run Logto at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A vulnerability exists in Logto's principal lookup mechanism within the Single Sign-On (SSO) guard and identity verification components. The application fails to normalize email and identifier strings (e.g., via case folding or Unicode normalization) before performing lookups. This allows for principal collisions where an attacker can register or authenticate using a visually or logically similar identifier (such as 'user@example.com' vs 'User@example.com' or Unicode equivalents) that the system treats as a different record during registration but matches to an existing principal during lookup. This can lead to unauthorized account access or session hijacking. The issue is present in versions 1.10.1 through 1.37.1.

Affected products

Logto Logto 1.10.1 to 1.37.1

Timeline

2026-07-23: disclosed
2026-07-23: advisory

References

https://github.com/logto-io/logto/blob/ea3ede35028dfd0bbb6d7b239623ce0e7f6cdff8/packages/core/src/libraries/verification-helpers/single-sign-on-guard.ts

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.