# CVE-2026-64046: net: tls: prevent chain-after-chain in plain text SG

> A flaw in the Linux kernel TLS implementation allows illegal scatterlist chaining, potentially causing a denial of service.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Jul 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-64046, DEBIAN-CVE-2026-64046, GHSA-3mwm-pxvj-5v4x, UBUNTU-CVE-2026-64046

## What is CVE-2026-64046?

CVE-2026-64046 is a critical vulnerability in Linux kernel, published on 19 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

net: tls: prevent chain-after-chain in plain text SG

Sashiko points out that if end = 0 (start != 0) the current
code will create a chain link to content type right after
the wrap link:

  This would create a chain where the wrap link points directly
  to another chain link. The scatterlist API sg_next iterator
  does not recursively resolve consecutive chain links.

meaning this is illegal input to crypto.

The wrapping link is unnecessary if end = 0. end is the entry after
the last one used so end = 0 means there's nothing pushed after
the wrap:

   end         start            i
    v            v              v
  [   ]...[   ][ d ][ d ][ d ][ d ][rsv for wrap]

Skip the wrapping in this case.

TLS 1.3 can use the "wrapping slot" for it's chaining if end = 0.
This avoids the chain-after-chain.

Move the wrap chaining before marking END and chaining off content
type, that feels like more logical ordering to me, but should not
matter from functional perspective.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-64046?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-64046?

Apply the vendor's patch.

## Is CVE-2026-64046 being exploited?

There is no known exploitation of CVE-2026-64046 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64046 and fix it if it is affected.

What it is: CVE-2026-64046 is a critical vulnerability in Linux kernel, published on 19 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-64046 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-64046/ (Markdown: https://insights.sbomify.com/CVE-2026-64046/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64046
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64046
- OSV: https://osv.dev/vulnerability/CVE-2026-64046

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64046/
Summaries are generated and may contain mistakes; the official description above is the record.