Temporal UI Server up to 2.53.1 Cookie missing secure attribute

Summaryinfo

A vulnerability categorized as problematic has been discovered in Temporal UI Server up to 2.53.1. This affects an unknown function of the component Cookie Handler. Such manipulation leads to missing secure attribute. This vulnerability is referenced as CVE-2026-65655. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Temporal UI Server up to 2.53.1. Affected by this issue is an unknown functionality of the component Cookie Handler. The manipulation with an unknown input leads to a missing secure attribute vulnerability. Using CWE to declare the problem leads to CWE-614. The Secure attribute for sensitive cookies in HTTPS sessions is not set, which could cause the user agent to send those cookies in plaintext over an HTTP session. Impacted is confidentiality. CVE summarizes:

When OAuth authentication is enabled and browser-facing TLS terminates at a reverse proxy that forwards the callback to Temporal UI Server over HTTP, affected versions derive authentication-cookie Secure attributes from the proxy-to-server connection. Temporal UI Server can therefore issue access-token cookies, and refresh-token cookies when provided by the identity provider, without Secure even though the browser completed login over HTTPS. A victim who visits attacker-controlled content while a credential remains live may expose that credential only if the attacker can also steer traffic for the UI hostname, prevent the browser's HTTPS connection from succeeding, serve the hostname over HTTP, and read a later same-site plaintext request. A malicious website alone cannot read the cookie, and passive observation of a successful TLS connection is insufficient. Effective HSTS, a blocking HTTPS-only warning, or TLS re-encryption between the proxy and Temporal UI Server prevents the demonstrated disclosure path. A recovered credential may be replayed within the victim's assigned permissions. Refresh-token replay additionally depends on the identity provider's issuance, expiry, rotation, and reuse-detection behavior.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-65655 since 07/22/2026. The exploitation is known to be difficult. The attack may be launched remotely. No form of authentication is required for exploitation. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1539 by the MITRE ATT&CK project.

Upgrading to version 2.53.2 eliminates this vulnerability.

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Productinfo

Vendor

• Temporal

Name

• UI Server

Version

• 2.53.0
• 2.53.1

CPE 2.3info

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CPE 2.2info

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• 🔒

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