# CVE-2023-45236: Predictable TCP ISNs in EDK II Network Package

> Predictable TCP Initial Sequence Numbers in EDK II allow attackers to bypass security controls and access confidential data.

- **Severity:** Medium 5.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Jan 2024
- **Updated:** 4 Nov 2025
- **Also known as:** AZL-38425, AZL-39388, AZL-39454, BELL-CVE-2023-45236, DEBIAN-CVE-2023-45236, GHSA-fqc4-ffq5-4r98

## What is CVE-2023-45236?

CVE-2023-45236 is a medium-severity vulnerability in TianoCore edk2, published on 16 Jan 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

EDK2's Network Package is susceptible to a predictable TCP Initial Sequence Number. This
 vulnerability can be exploited by an attacker to gain unauthorized 
access and potentially lead to a loss of Confidentiality.

Weakness: CWE-338 (Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)), CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2023-45236?

It affects 1 product.


Products: Tianocore Edk2.

## How do I fix CVE-2023-45236?

Apply the vendor's patch.

## Is CVE-2023-45236 being exploited?

There is no known exploitation of CVE-2023-45236 in the wild and no public exploit code.

## Other vulnerabilities in TianoCore edk2

- [CVE-2023-45230](https://insights.sbomify.com/CVE-2023-45230/): Buffer Overflow in EDK II Network Package (high 8.3)
- [CVE-2023-45234](https://insights.sbomify.com/CVE-2023-45234/): Buffer Overflow in EDK II Network Package (high 8.3)
- [CVE-2023-45235](https://insights.sbomify.com/CVE-2023-45235/): Buffer Overflow in EDK II Network Package (high 8.3)
- [CVE-2021-28210](https://insights.sbomify.com/CVE-2021-28210/): Denial of service in EDK II (high 7.8)
- [CVE-2019-14584](https://insights.sbomify.com/CVE-2019-14584/): Null dereference in Tianocore EDK2 (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-45236 and fix it if it is affected.

What it is: CVE-2023-45236 is a medium-severity vulnerability in TianoCore edk2, published on 16 Jan 2024. 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-2023-45236 in the wild and no public exploit code.

Affected product: TianoCore edk2. 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-2023-45236/ (Markdown: https://insights.sbomify.com/CVE-2023-45236/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-45236
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-45236
- OSV: https://osv.dev/vulnerability/CVE-2023-45236

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-45236/
Summaries are generated and may contain mistakes; the official description above is the record.