# CVE-2018-6551: Integer overflow in n/a

> An integer overflow in glibc malloc can cause heap corruption, potentially leading to code execution or denial of service.

- **Severity:** Critical 9.8 (`CVSS:3.0/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:** Yes
- **Published:** 2 Feb 2018
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2018-6551, GHSA-39wv-6252-46w2

## What is CVE-2018-6551?

CVE-2018-6551 is a critical vulnerability in Gnu Glibc, published on 2 Feb 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The malloc implementation in the GNU C Library (aka glibc or libc6), from version 2.24 to 2.26 on powerpc, and only in version 2.26 on i386, did not properly handle malloc calls with arguments close to SIZE_MAX and could return a pointer to a heap region that is smaller than requested, eventually leading to heap corruption.

Weakness: CWE-787 (Out-of-bounds Write), CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2018-6551?

It affects 1 product.


Products: Gnu Glibc.

## How do I fix CVE-2018-6551?

Upgrade to a fixed version.

## Is CVE-2018-6551 being exploited?

There is no known exploitation of CVE-2018-6551 in the wild and no public exploit code.

## Other vulnerabilities in Gnu Glibc

- [CVE-2026-5450](https://insights.sbomify.com/CVE-2026-5450/): scanf %mc off-by-one heap buffer overflow (critical 9.8)
- [CVE-2023-25139](https://insights.sbomify.com/CVE-2023-25139/): Memory corruption in n/a (critical 9.8)
- [CVE-1999-0199](https://insights.sbomify.com/CVE-1999-0199/): Other in n/a (critical 9.8)
- [CVE-2019-1010022](https://insights.sbomify.com/CVE-2019-1010022/): Security feature bypass in glibc (critical 9.8)
- [CVE-2005-3590](https://insights.sbomify.com/CVE-2005-3590/): Memory corruption in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-6551 and fix it if it is affected.

What it is: CVE-2018-6551 is a critical vulnerability in Gnu Glibc, published on 2 Feb 2018. 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-2018-6551 in the wild and no public exploit code.

Affected product: Gnu Glibc. 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-2018-6551/ (Markdown: https://insights.sbomify.com/CVE-2018-6551/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-6551
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-6551
- OSV: https://osv.dev/vulnerability/CVE-2018-6551

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-6551/
Summaries are generated and may contain mistakes; the official description above is the record.