# CVE-2026-99059: wireguard: noise: reject response consumption after intermediate initiation


- **Severity:** High 7.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 23 Oct 2026
- **Updated:** 24 Oct 2026
- **Also known as:** AZL-110948, BELL-CVE-2026-99059, DEBIAN-CVE-2026-99059, GHSA-c2jq-9mfv-9wqh, UBUNTU-CVE-2026-99059

## What is CVE-2026-99059?

CVE-2026-99059 is a high-severity vulnerability in Linux, published on 23 Oct 2026. 

### Official description

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.

## Which versions are affected by CVE-2026-99059?


## How do I fix CVE-2026-99059?

Upgrade to a fixed version.

## Is CVE-2026-99059 being exploited?

There is no known exploitation of CVE-2026-99059 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-99059 and fix it if it is affected.

What it is: CVE-2026-99059 is a high-severity vulnerability in Linux, published on 23 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-99059 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-99059/ (Markdown: https://insights.sbomify.com/CVE-2026-99059/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-99059
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-99059
- OSV: https://osv.dev/vulnerability/CVE-2026-99059

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-99059/
Summaries are generated and may contain mistakes; the official description above is the record.