Is CVE-2026-53425 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-53425 being exploited in the wild.

How severe is CVE-2026-53425?

Informational severity, published 20 August 2026.

Is there a fix for CVE-2026-53425?

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-2026-53425 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-53425?

Check whether anything you run is named in the advisory. 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-2026-53425: Dropbox Samly SAML authentication bypass

CVE-2026-53425 · Severity: info · Published 2026-08-20

Samly is a library used to integrate SAML single sign-on authentication into applications. A vulnerability in its SAML response validation allows an attacker to hijack a victim's authenticated session by replaying a SAML response from the trusted identity provider without verifying the response matches a specific login request. This could allow unauthorized access to accounts without knowing passwords.

Quick answers

Is CVE-2026-53425 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-53425 being exploited in the wild.
How severe is CVE-2026-53425?: Informational severity, published 20 August 2026.
Which products and versions are affected?: Dropbox Samly 0.3.0 and later.
Is there a fix for CVE-2026-53425?: 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-2026-53425 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-53425?: Check whether anything you run is named in the advisory. 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

The vulnerability is an insufficient verification of data authenticity in Samly's SPHandler.validate_authresp/3 function. The code validates SAML responses by checking RelayState, IdP identifier, and session target URL, but fails to verify that the SubjectConfirmationData/@InResponseTo attribute matches the ID of the AuthnRequest originally issued by the service provider. SAML 2.0 Core section 4.1.4.3 mandates this check to prevent response replay attacks. Exploitation requires a validly signed SAML assertion from the trusted IdP (obtainable using the attacker's own account) and knowledge of a victim's RelayState session value. The underlying esaml library also does not verify InResponseTo, closing no alternative validation path. No patch information is currently available.

Affected products

Dropbox Samly 0.3.0 and later

Timeline

2026-08-20: disclosed

References

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