CVE-2026-99059 is a vulnerability in Linux Kernel
Published on October 23, 2026
wireguard: noise: reject response consumption after intermediate initiation
In the Linux kernel, the following vulnerability has been resolved:
wireguard: noise: reject response consumption after intermediate initiation
Two threads begin processing the identical response message, received
twice. The first thread, A, runs. While it's running, the second one,
B, gets partway through, and during that slow calculation, or even while
blocking on down_write(), A completes and then also a handshake
initiation that's already been queued up runs in thread C, which itself
takes that same down_write(). The handshake initiation creation
succeeds, and sets the state back to waiting-for-response, and calls
up_write(), at which point thread B resumes, because either its finished
its calculations or was finally allowed to acquire down_write(). Thread
B then copies the state back to the peer, and begins a new session,
using that state, which is the same session as the one made in thread A.
Thread A Thread B Thread C
down_read()
sA = handshake->state
memcpy(cA, handshake->crypto)
up_read()
if (sA != 1)
goto fail
slow_crypto(cA)
down_read()
sB = handshake->state
memcpy(cB, handshake->crypto)
up_read()
if (sB != 1)
goto fail
slow_crypto(cB)
down_write()
if (sA != handshake->state)
goto fail
memcpy(handshake->crypto, cA)
handshake->state = 2
up_write()
down_write()
if (handshake->state != 2)
goto fail
derive_session(handshake->crypto)
up_write()
down_write()
slow_crypto(handshake->crypto)
handshake->state = 1
up_write()
down_write()
if (sB != handshake->state)
goto fail
memcpy(handshake->crypto, cB)
handshake->state = 2
up_write()
down_write()
if (handshake->state != 2)
goto fail
derive_session(handshake->crypto)
up_write()
This seems basically impossible to hit in a meaningful way in practice,
but ensure that it absolutely cannot happen by comparing the ephemeral
private key that's on the stack with the latest one that the peer's
handshake state has.
Products Associated with CVE-2026-99059
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Affected Versions
Linux:- Version e7096c131e5161fa3b8e52a650d7719d2857adfd and below fb5ce4c7790c3eeec820302d08d70ecf46af4295 is affected.
- Version e7096c131e5161fa3b8e52a650d7719d2857adfd and below c76a80db593096edf2b3b3972f58b6342a8c6c04 is affected.
- Version e7096c131e5161fa3b8e52a650d7719d2857adfd and below 4d64a3d6e96aa78619c9c29ffde309794974588a is affected.
- Version e7096c131e5161fa3b8e52a650d7719d2857adfd and below 3bec3d32c2a3afd164fc87f95457df2cf9049c20 is affected.
- Version e7096c131e5161fa3b8e52a650d7719d2857adfd and below d0305f8d90029556260c6824b61c493c424eba9e is affected.
- Version 5.6 is affected.
- Before 5.6 is unaffected.
- Version 6.6.160, <= 6.6.* is unaffected.
- Version 6.12.113, <= 6.12.* is unaffected.
- Version 6.18.57, <= 6.18.* is unaffected.
- Version 7.2.11, <= 7.2.* is unaffected.
- Version 7.3, <= * is unaffected.