# CVE-2021-31349: Session Smart Router: Authentication Bypass Vulnerability

> An attacker can bypass authentication via an internal HTTP header to view files, change settings, and execute arbitrary code on Juniper Session Smart Routers.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:** 19 Oct 2021
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-4r2w-j4p7-rw4p

## What is CVE-2021-31349?

CVE-2021-31349 is a critical authentication bypass vulnerability in Juniper Networks 128 Technology Session Smart Router, published on 19 Oct 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The usage of an internal HTTP header created an authentication bypass vulnerability (CWE-287), allowing an attacker to view internal files, change settings, manipulate services and execute arbitrary code. This issue affects all Juniper Networks 128 Technology Session Smart Router versions prior to 4.5.11, and all versions of 5.0 up to and including 5.0.1.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2021-31349?

It affects 1 product.


Products: Juniper 128 Technology Session Smart Router Firmware.

## How do I fix CVE-2021-31349?

No fix has been published for CVE-2021-31349 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-31349 being exploited?

There is no known exploitation of CVE-2021-31349 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-31349 and fix it if it is affected.

What it is: CVE-2021-31349 is a critical authentication bypass vulnerability in Juniper Networks 128 Technology Session Smart Router, published on 19 Oct 2021. 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-2021-31349 in the wild and no public exploit code.

Affected product: Juniper Networks 128 Technology Session Smart Router. 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-2021-31349/ (Markdown: https://insights.sbomify.com/CVE-2021-31349/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-31349
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-31349
- OSV: https://osv.dev/vulnerability/CVE-2021-31349

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-31349/
Summaries are generated and may contain mistakes; the official description above is the record.