# CVE-2023-36843: Junos OS: SRX Series: The PFE will crash on receiving malformed SSL traffic when Sky ATP is enabled

> Unauthenticated attackers can crash the Packet Forwarding Engine via malformed SSL traffic if Sky ATP is enabled, requiring a manual restart.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/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 Oct 2023
- **Updated:** 18 Sep 2024
- **Also known as:** GHSA-f8h4-8cx8-j35m

## What is CVE-2023-36843?

CVE-2023-36843 is a high-severity denial of service vulnerability in Juniper Junos, published on 12 Oct 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An Improper Handling of Inconsistent Special Elements vulnerability in the Junos Services Framework (jsf) module of Juniper Networks Junos OS allows an unauthenticated network based attacker to cause a crash in the Packet Forwarding Engine (pfe) and thereby resulting in a Denial of Service (DoS).

Upon receiving malformed SSL traffic, the PFE crashes. A manual restart will be needed to recover the device.

This issue only affects devices with Juniper Networks Advanced Threat Prevention (ATP) Cloud enabled with Encrypted Traffic Insights (configured via ‘security-metadata-streaming policy’).

This issue affects Juniper Networks Junos OS:

  *  All versions prior to 20.4R3-S8, 20.4R3-S9;
  *  21.1 version 21.1R1 and later versions;
  *  21.2 versions prior to 21.2R3-S6;
  *  21.3 versions prior to 21.3R3-S5;
  *  21.4 versions prior to 21.4R3-S5;
  *  22.1 versions prior to 22.1R3-S4;
  *  22.2 versions prior to 22.2R3-S2;
  *  22.3 versions prior to 22.3R2-S2, 22.3R3;
  *  22.4 versions prior to 22.4R2-S1, 22.4R3;

Weakness: CWE-168 (Improper Handling of Inconsistent Special Elements)

## Which versions are affected by CVE-2023-36843?

It affects 1 product.


Products: Juniper Junos.

## How do I fix CVE-2023-36843?

No fix has been published for CVE-2023-36843 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-36843 being exploited?

There is no known exploitation of CVE-2023-36843 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-2023-36843 and fix it if it is affected.

What it is: CVE-2023-36843 is a high-severity denial of service vulnerability in Juniper Junos, published on 12 Oct 2023. 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-2023-36843 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-2023-36843/ (Markdown: https://insights.sbomify.com/CVE-2023-36843/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-36843
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-36843
- OSV: https://osv.dev/vulnerability/CVE-2023-36843

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-36843/
Summaries are generated and may contain mistakes; the official description above is the record.