# CVE-2024-21601: Junos OS: SRX Series: Due to an error in processing TCP events flowd will crash

> An unauthenticated attacker can cause a sustained denial of service on Juniper SRX devices by triggering a race condition in the flow processing daemon.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Jan 2024
- **Updated:** 14 Nov 2024
- **Also known as:** GHSA-5mjf-6gr5-jvh8

## What is CVE-2024-21601?

CVE-2024-21601 is a medium-severity vulnerability in Juniper Junos, published on 12 Jan 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') vulnerability in the Flow-processing Daemon (flowd) of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (Dos).

On SRX Series devices when two different threads try to simultaneously process a queue which is used for TCP events flowd will crash. One of these threads can not be triggered externally, so the exploitation of this race condition is outside the attackers direct control.

Continued exploitation of this issue will lead to a sustained DoS.

This issue affects Juniper Networks Junos OS:

  *  21.2 versions earlier than 21.2R3-S5;
  *  21.3 versions earlier than 21.3R3-S5;
  *  21.4 versions earlier than 21.4R3-S4;
  *  22.1 versions earlier than 22.1R3-S3;
  *  22.2 versions earlier than 22.2R3-S1;
  *  22.3 versions earlier than 22.3R2-S2, 22.3R3;
  *  22.4 versions earlier than 22.4R2-S1, 22.4R3.

This issue does not affect Juniper Networks Junos OS versions earlier than 21.2R1.

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2024-21601?

It affects 1 product.


Products: Juniper Junos.

## How do I fix CVE-2024-21601?

No fix has been published for CVE-2024-21601 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-21601 being exploited?

There is no known exploitation of CVE-2024-21601 in the wild and no public exploit code.

## Other vulnerabilities in Juniper Junos

- [CVE-2023-36845](https://insights.sbomify.com/CVE-2023-36845/): Juniper Junos OS EX Series and SRX Series PHP External Variable Modification (critical 9.8, exploited in the wild)
- [CVE-2020-1631](https://insights.sbomify.com/CVE-2020-1631/): Juniper Junos OS Path Traversal (high 8.8, exploited in the wild)
- [CVE-2025-21590](https://insights.sbomify.com/CVE-2025-21590/): Juniper Junos OS Improper Isolation or Compartmentalization (medium 6.7, exploited in the wild)
- [CVE-2023-36851](https://insights.sbomify.com/CVE-2023-36851/): Juniper Junos OS SRX Series Missing Authentication for Critical Function (medium 5.3, exploited in the wild)
- [CVE-2023-36844](https://insights.sbomify.com/CVE-2023-36844/): Juniper Junos OS EX Series PHP External Variable Modification (medium 5.3, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-21601 and fix it if it is affected.

What it is: CVE-2024-21601 is a medium-severity vulnerability in Juniper Junos, published on 12 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-2024-21601 in the wild and no public exploit code.

Affected product: Juniper Junos. 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-2024-21601/ (Markdown: https://insights.sbomify.com/CVE-2024-21601/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-21601
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-21601
- OSV: https://osv.dev/vulnerability/CVE-2024-21601

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-21601/
Summaries are generated and may contain mistakes; the official description above is the record.