# CVE-2018-16890: Integer overflow in curl

> A malicious NTLM server can trigger an integer overflow in libcurl, leading to an out-of-bounds read that may disclose memory or cause a crash.

- **Severity:** Medium 5.4 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 6 Feb 2019
- **Updated:** 15 Apr 2026
- **Also known as:** ALPINE-CVE-2018-16890, CLEANSTART-2026-OR86338, CURL-CVE-2018-16890, DEBIAN-CVE-2018-16890, GHSA-53fg-3j53-939q, UBUNTU-CVE-2018-16890

## What is CVE-2018-16890?

CVE-2018-16890 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 6 Feb 2019. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

libcurl versions from 7.36.0 to before 7.64.0 is vulnerable to a heap buffer out-of-bounds read. The function handling incoming NTLM type-2 messages (`lib/vauth/ntlm.c:ntlm_decode_type2_target`) does not validate incoming data correctly and is subject to an integer overflow vulnerability. Using that overflow, a malicious or broken NTLM server could trick libcurl to accept a bad length + offset combination that would lead to a buffer read out-of-bounds.

Weakness: CWE-190 (Integer Overflow or Wraparound), CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2018-16890?

It affects 10 products.


Products: Canonical Ubuntu Linux, Debian Debian Linux, F5 Big-Ip Access Policy Manager, Haxx Libcurl, Netapp Clustered Data Ontap, Oracle Communications Operations Monitor, Oracle Http Server, Oracle Secure Global Desktop, Redhat Enterprise Linux, Siemens Sinema Remote Connect Client.

## How do I fix CVE-2018-16890?

Upgrade to a fixed version.

## Is CVE-2018-16890 being exploited?

There is no known exploitation of CVE-2018-16890 in the wild and no public exploit code.

Public exploit code:

- CVE-2018-16890 (github_poc): https://github.com/michelleamesquita/CVE-2018-16890

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-16890 and fix it if it is affected.

What it is: CVE-2018-16890 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 6 Feb 2019. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2018-16890 in the wild and no public exploit code.

Affected product: Canonical Ubuntu Linux. 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-2018-16890/ (Markdown: https://insights.sbomify.com/CVE-2018-16890/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-16890
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-16890
- OSV: https://osv.dev/vulnerability/CVE-2018-16890

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From sbomify Insights: https://insights.sbomify.com/CVE-2018-16890/
Summaries are generated and may contain mistakes; the official description above is the record.