CVE-2026-65655 Temporal UI Server may set OAuth credential cookies without Secure behind a TLS-terminating reverse proxy
Attackers can steal OAuth cookies if TLS terminates at a proxy and traffic is downgraded, allowing account takeover within user permissions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-65655?
CVE-2026-65655 is a low-severity vulnerability in Temporal UI Server, published on 11 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
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.
Weakness: CWE-614
Which versions are affected by CVE-2026-65655?
How do I fix CVE-2026-65655?
No fix has been published for CVE-2026-65655 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-65655 being exploited?
There is no known exploitation of CVE-2026-65655 in the wild and no public exploit code.
Sources
Also known as GHSA-c7mm-29xf-mmqp.