# CVE-2023-4807: POLY1305 MAC implementation corrupts XMM registers on Windows

> OpenSSL corrupts XMM registers on Windows with AVX512, potentially causing crashes or code execution in applications using POLY1305.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 8 Sep 2023
- **Updated:** 14 Oct 2026
- **Also known as:** AZL-39646, AZL-78585, GHSA-53wr-cx66-4578, JLSEC-2026-242, openSUSE-SU-2024:13241-1, openSUSE-SU-2024:13275-1

## What is CVE-2023-4807?

CVE-2023-4807 is a high-severity memory corruption vulnerability in Openssl Openssl, published on 8 Sep 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Issue summary: The POLY1305 MAC (message authentication code) implementation
contains a bug that might corrupt the internal state of applications on the
Windows 64 platform when running on newer X86_64 processors supporting the
AVX512-IFMA instructions.

Impact summary: If in an application that uses the OpenSSL library an attacker
can influence whether the POLY1305 MAC algorithm is used, the application
state might be corrupted with various application dependent consequences.

The POLY1305 MAC (message authentication code) implementation in OpenSSL does
not save the contents of non-volatile XMM registers on Windows 64 platform
when calculating the MAC of data larger than 64 bytes. Before returning to
the caller all the XMM registers are set to zero rather than restoring their
previous content. The vulnerable code is used only on newer x86_64 processors
supporting the AVX512-IFMA instructions.

The consequences of this kind of internal application state corruption can
be various - from no consequences, if the calling application does not
depend on the contents of non-volatile XMM registers at all, to the worst
consequences, where the attacker could get complete control of the application
process. However given the contents of the registers are just zeroized so
the attacker cannot put arbitrary values inside, the most likely consequence,
if any, would be an incorrect result of some application dependent
calculations or a crash leading to a denial of service.

The POLY1305 MAC algorithm is most frequently used as part of the
CHACHA20-POLY1305 AEAD (authenticated encryption with associated data)
algorithm. The most common usage of this AEAD cipher is with TLS protocol
versions 1.2 and 1.3 and a malicious client can influence whether this AEAD
cipher is used by the server. This implies that server applications using
OpenSSL can be potentially impacted. However we are currently not aware of
any concrete application that would be affected by this issue therefore we
consider this a Low severity security issue.

As a workaround the AVX512-IFMA instructions support can be disabled at
runtime by setting the environment variable OPENSSL_ia32cap:

   OPENSSL_ia32cap=:~0x200000

The FIPS provider is not affected by this issue.

Weakness: CWE-440 (Expected Behavior Violation)

## Which versions are affected by CVE-2023-4807?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `openssl-1_1` | openSUSE:Tumbleweed | All versions | 1.1.1w-1.1 |
| `openssl-3` | openSUSE:Tumbleweed | All versions | 3.1.3-1.2 |

Products: Openssl Openssl.

## How do I fix CVE-2023-4807?

Apply the vendor's patch.

## Is CVE-2023-4807 being exploited?

There is no known exploitation of CVE-2023-4807 in the wild and no public exploit code.

## Other vulnerabilities in Openssl Openssl

- [CVE-2009-3245](https://insights.sbomify.com/CVE-2009-3245/): Null dereference in n/a (critical 10.0)
- [CVE-2006-3738](https://insights.sbomify.com/CVE-2006-3738/): Memory corruption in n/a (critical 10.0)
- [CVE-2026-63073](https://insights.sbomify.com/CVE-2026-63073/): Untrusted Sender DN Used as Format String in CMP Response Validation (critical 9.8)
- [CVE-2016-6309](https://insights.sbomify.com/CVE-2016-6309/): Use after free in n/a (critical 9.8)
- [CVE-2016-0799](https://insights.sbomify.com/CVE-2016-0799/): Integer overflow in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-4807 and fix it if it is affected.

What it is: CVE-2023-4807 is a high-severity memory corruption vulnerability in Openssl Openssl, published on 8 Sep 2023. 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-2023-4807 in the wild and no public exploit code.

Affected product: Openssl Openssl. 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-2023-4807/ (Markdown: https://insights.sbomify.com/CVE-2023-4807/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-4807
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-4807
- OSV: https://osv.dev/vulnerability/CVE-2023-4807

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-4807/
Summaries are generated and may contain mistakes; the official description above is the record.