# CVE-2023-52874: x86/tdx: Zero out the missing RSI in TDX_HYPERCALL macro

> A missing register zeroing in the Linux kernel TDX hypercall allows a malicious VMM to leak sensitive data via speculative execution.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 21 May 2024
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2023-52874, DEBIAN-CVE-2023-52874, GHSA-5h67-9rvr-r9x6, UBUNTU-CVE-2023-52874

## What is CVE-2023-52874?

CVE-2023-52874 is a high-severity vulnerability in Linux kernel, published on 21 May 2024. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

x86/tdx: Zero out the missing RSI in TDX_HYPERCALL macro

In the TDX_HYPERCALL asm, after the TDCALL instruction returns from the
untrusted VMM, the registers that the TDX guest shares to the VMM need
to be cleared to avoid speculative execution of VMM-provided values.

RSI is specified in the bitmap of those registers, but it is missing
when zeroing out those registers in the current TDX_HYPERCALL.

It was there when it was originally added in commit 752d13305c78
("x86/tdx: Expand __tdx_hypercall() to handle more arguments"), but was
later removed in commit 1e70c680375a ("x86/tdx: Do not corrupt
frame-pointer in __tdx_hypercall()"), which was correct because %rsi is
later restored in the "pop %rsi".  However a later commit 7a3a401874be
("x86/tdx: Drop flags from __tdx_hypercall()") removed that "pop %rsi"
but forgot to add the "xor %rsi, %rsi" back.

Fix by adding it back.

## Which versions are affected by CVE-2023-52874?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-52874?

Apply the vendor's patch.

## Is CVE-2023-52874 being exploited?

There is no known exploitation of CVE-2023-52874 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-2023-52874 and fix it if it is affected.

What it is: CVE-2023-52874 is a high-severity vulnerability in Linux kernel, published on 21 May 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-52874 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-2023-52874/ (Markdown: https://insights.sbomify.com/CVE-2023-52874/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-52874
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-52874
- OSV: https://osv.dev/vulnerability/CVE-2023-52874

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-52874/
Summaries are generated and may contain mistakes; the official description above is the record.