Privasys Intra-handshake attested TLS implementation is vulnerable to TOCTOU Attacks

Privasys Remote Attestation TLS Clients provides multi-language utilities for verifying attested TLS connections. Before 0.9.1, an attacker with local access could modify workload code, data, and configuration at any time after successful connection establishment. Once Evidence was successfully appraised and the connection was established, there was a window of vulnerability from the establishment of the connection to the termination of the connection where an attacker could modify the state of the workload and platform at runtime on the TLS endpoint acting as the Attester. This vulnerability was possible because Privasys/ra-tls-clients performed attestation only once in the lifetime of the connection (at connection establishment time), and the verifying peer continued to believe that the state was the same as in the initial Evidence throughout, whereas it could be stale at some point in time. This vulnerability is fixed in 0.9.1.

Source published

12 Oct 2026 19:06:20 UTC

Source modified

15 Oct 2026 13:41:30 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

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CVSS 4.0 · 7.2 CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N