# CVE-2026-31533: net/tls: fix use-after-free in -EBUSY error path of tls_do_encryption

> A use-after-free in the Linux kernel's TLS encryption path allows attackers to execute arbitrary code or escalate privileges via crafted network traffic.

- **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:** 23 Apr 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-85067, BELL-CVE-2026-31533, DEBIAN-CVE-2026-31533, GHSA-r7wv-m72q-8qj8, ROOT-OS-DEBIAN-12-CVE-2026-31533, ROOT-OS-DEBIAN-13-CVE-2026-31533, ROOT-OS-UBUNTU-2204-CVE-2026-31533, ROOT-OS-UBUNTU-2404-CVE-2026-31533

## What is CVE-2026-31533?

CVE-2026-31533 is a critical use after free vulnerability in Linux kernel, published on 23 Apr 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: fix use-after-free in -EBUSY error path of tls_do_encryption

The -EBUSY handling in tls_do_encryption(), introduced by commit
859054147318 ("net: tls: handle backlogging of crypto requests"), has
a use-after-free due to double cleanup of encrypt_pending and the
scatterlist entry.

When crypto_aead_encrypt() returns -EBUSY, the request is enqueued to
the cryptd backlog and the async callback tls_encrypt_done() will be
invoked upon completion. That callback unconditionally restores the
scatterlist entry (sge->offset, sge->length) and decrements
ctx->encrypt_pending. However, if tls_encrypt_async_wait() returns an
error, the synchronous error path in tls_do_encryption() performs the
same cleanup again, double-decrementing encrypt_pending and
double-restoring the scatterlist.

The double-decrement corrupts the encrypt_pending sentinel (initialized
to 1), making tls_encrypt_async_wait() permanently skip the wait for
pending async callbacks. A subsequent sendmsg can then free the
tls_rec via bpf_exec_tx_verdict() while a cryptd callback is still
pending, resulting in a use-after-free when the callback fires on the
freed record.

Fix this by skipping the synchronous cleanup when the -EBUSY async
wait returns an error, since the callback has already handled
encrypt_pending and sge restoration.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-31533?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31533?

Apply the vendor's patch.

## Is CVE-2026-31533 being exploited?

There is no known exploitation of CVE-2026-31533 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-2026-31533 and fix it if it is affected.

What it is: CVE-2026-31533 is a critical use after free vulnerability in Linux kernel, published on 23 Apr 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-2026-31533 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-2026-31533/ (Markdown: https://insights.sbomify.com/CVE-2026-31533/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31533
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31533
- OSV: https://osv.dev/vulnerability/CVE-2026-31533

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31533/
Summaries are generated and may contain mistakes; the official description above is the record.