Details for this vulnerability have not been published by NIST at this point. Descriptions from software vendor advisories for this issue are provided below.
From VID-E0F26AC5-6A17-11ED-93E7-901B0E9408DC:
Tailscale team reports:
A vulnerability identified in the Tailscale client allows a
malicious website to access the peer API, which can then be used
to access Tailscale environment variables.
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