Foreshadow, known as L1 Terminal Fault (L1TF) by Intel,[1][2] is a vulnerability that affects modern microprocessors that was first discovered by two independent teams of researchers in January 2018, but was first disclosed to the public on 14 August 2018.

[18] The vulnerability is a speculative execution attack on Intel processors that may result in the disclosure of sensitive information stored in personal computers and third-party clouds.

[7] According to one expert, "[Foreshadow] lets malicious software break into secure areas that even the Spectre and Meltdown flaws couldn't crack".

[9][22] Two groups of researchers discovered the security vulnerabilities independently: a Belgian team (including Raoul Strackx, Jo Van Bulck, Frank Piessens) from imec-DistriNet, KU Leuven reported it to Intel on 3 January 2018;[23] a second team from Technion – Israel Institute of Technology (Marina Minkin, Mark Silberstein), University of Adelaide (Yuval Yarom), and University of Michigan (Ofir Weisse, Daniel Genkin, Baris Kasikci, Thomas F. Wenisch) reported it on 23 January 2018.

[1][4] The Foreshadow vulnerability is a speculative execution attack on Intel processors that may result in the disclosure of sensitive information stored in personal computers and third-party clouds.

[1] Intel considers the entire class of speculative execution side channel vulnerabilities as "L1 Terminal Fault" (L1TF).

[7] According to one expert, "[Foreshadow] lets malicious software break into secure areas that even the Spectre and Meltdown flaws couldn't crack".