Shortly before the release of the 5.8 kernel, a brief patch to a
pseudo-random-number generator (PRNG) used by the networking stack was quietly
applied to the kernel. As is the norm for such things, the changelog gave
no indication that a security vulnerability had been fixed, but that turns
out indeed to be the case. The resulting controversy had little to do with
the original vulnerability, though, and everything to do with how
cryptographic security is managed in the kernel. Figuring prominently in
the discussion was
the question of whether theoretical security can undermine security in the
real world.

Source: LWN.net – [$] Theoretical vs. practical cryptography in the kernel