# CVE-2018-15453: Cisco Email Security Appliance Memory Corruption Denial of Service Vulnerability

> Remote attackers can cause permanent denial of service on Cisco ESA devices via malicious S/MIME emails if specific features are enabled.

- **Severity:** High 8.6 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/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:** 10 Jan 2019
- **Updated:** 19 Nov 2024
- **Also known as:** GHSA-62wx-gppg-6grr

## What is CVE-2018-15453?

CVE-2018-15453 is a high-severity memory corruption vulnerability in Cisco Email Security Appliance (ESA), published on 10 Jan 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the Secure/Multipurpose Internet Mail Extensions (S/MIME) Decryption and Verification or S/MIME Public Key Harvesting features of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to cause an affected device to corrupt system memory. A successful exploit could cause the filtering process to unexpectedly reload, resulting in a denial of service (DoS) condition on the device. The vulnerability is due to improper input validation of S/MIME-signed emails. An attacker could exploit this vulnerability by sending a malicious S/MIME-signed email through a targeted device. If Decryption and Verification or Public Key Harvesting is configured, the filtering process could crash due to memory corruption and restart, resulting in a DoS condition. The software could then resume processing the same S/MIME-signed email, causing the filtering process to crash and restart again. A successful exploit could allow the attacker to cause a permanent DoS condition. This vulnerability may require manual intervention to recover the ESA.

Weakness: CWE-787 (Out-of-bounds Write), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2018-15453?

It affects 1 product.


Products: Cisco Email Security Appliance Firmware.

## How do I fix CVE-2018-15453?

No fix has been published for CVE-2018-15453 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-15453 being exploited?

There is no known exploitation of CVE-2018-15453 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Email Security Appliance (ESA)

- [CVE-2016-6406](https://insights.sbomify.com/CVE-2016-6406/): Auth bypass in n/a (critical 9.8)
- [CVE-2017-6671](https://insights.sbomify.com/CVE-2017-6671/): Security feature bypass in Cisco Email Security Appliance (high 7.5)
- [CVE-2016-6458](https://insights.sbomify.com/CVE-2016-6458/): Security feature bypass in Cisco AsyncOS 10.0.0-125 and 9.7.1-066 (high 7.5)
- [CVE-2019-12706](https://insights.sbomify.com/CVE-2019-12706/): Cisco Email Security Appliance Filter Bypass Vulnerability (medium 6.5)
- [CVE-2019-15971](https://insights.sbomify.com/CVE-2019-15971/): Cisco Email Security Appliance MP3 Content Filter Bypass Vulnerability (medium 5.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-15453 and fix it if it is affected.

What it is: CVE-2018-15453 is a high-severity memory corruption vulnerability in Cisco Email Security Appliance (ESA), published on 10 Jan 2019. 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-2018-15453 in the wild and no public exploit code.

Affected product: Cisco Email Security Appliance (ESA). 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-2018-15453/ (Markdown: https://insights.sbomify.com/CVE-2018-15453/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-15453
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-15453
- OSV: https://osv.dev/vulnerability/CVE-2018-15453

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From sbomify Insights: https://insights.sbomify.com/CVE-2018-15453/
Summaries are generated and may contain mistakes; the official description above is the record.