# CVE-2015-6321: Denial of service in n/a

> Remote attackers can cause denial of service via TCP packet floods on Cisco Email, Content, and Web Security Appliances.

- **Severity:** High 7.8 (`AV:N/AC:L/Au:N/C:N/I:N/A:C`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 6 Nov 2015
- **Updated:** 6 Aug 2024
- **Also known as:** GHSA-rmcx-cqh3-x8cj

## What is CVE-2015-6321?

CVE-2015-6321 is a high-severity denial of service vulnerability in Cisco Email Security Appliance, published on 6 Nov 2015. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Cisco AsyncOS before 8.5.7-042, 9.x before 9.1.0-032, 9.1.x before 9.1.1-023, and 9.5.x and 9.6.x before 9.6.0-042 on Email Security Appliance (ESA) devices; before 9.1.0-032, 9.1.1 before 9.1.1-005, and 9.5.x before 9.5.0-025 on Content Security Management Appliance (SMA) devices; and before 7.7.0-725 and 8.x before 8.0.8-113 on Web Security Appliance (WSA) devices allows remote attackers to cause a denial of service (memory consumption) via a flood of TCP packets, aka Bug IDs CSCus79774, CSCus79777, and CSCzv95795.

Weakness: CWE-399

## Which versions are affected by CVE-2015-6321?

It affects 3 products.


Products: Cisco Content Security Management Appliance, Cisco Email Security Appliance, Cisco Web Security Appliance.

## How do I fix CVE-2015-6321?

No fix has been published for CVE-2015-6321 yet. Limit exposure of the affected software until one is available.

## Is CVE-2015-6321 being exploited?

There is no known exploitation of CVE-2015-6321 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Email Security Appliance

- [CVE-2014-2119](https://insights.sbomify.com/CVE-2014-2119/): File upload in n/a (high 8.5)
- [CVE-2013-5537](https://insights.sbomify.com/CVE-2013-5537/): Denial of service in n/a (high 7.8)
- [CVE-2016-2183](https://insights.sbomify.com/CVE-2016-2183/): Weak cryptography in n/a (high 7.5)
- [CVE-2013-3395](https://insights.sbomify.com/CVE-2013-3395/): Cross-site request forgery in n/a (medium 6.8)
- [CVE-2021-1447](https://insights.sbomify.com/CVE-2021-1447/): Cisco Content Security Management Appliance Privilege Escalation Vulnerability (medium 6.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2015-6321 and fix it if it is affected.

What it is: CVE-2015-6321 is a high-severity denial of service vulnerability in Cisco Email Security Appliance, published on 6 Nov 2015. 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-2015-6321 in the wild and no public exploit code.

Affected product: Cisco Email Security Appliance. 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-2015-6321/ (Markdown: https://insights.sbomify.com/CVE-2015-6321/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2015-6321
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2015-6321
- OSV: https://osv.dev/vulnerability/CVE-2015-6321

---
From sbomify Insights: https://insights.sbomify.com/CVE-2015-6321/
Summaries are generated and may contain mistakes; the official description above is the record.