# OSV-2021-696: UNKNOWN READ in ntlm_decode_type2_target

> An out-of-bounds read in cURL's NTLM authentication decoding can cause a crash, potentially leading to denial of service.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not stated
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 28 Apr 2021

## What is OSV-2021-696?

OSV-2021-696 is a memory corruption vulnerability in curl, published on 28 Apr 2021. It can be exploited over the network, with no action from the victim.

### Official description

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=33720

```
Crash type: UNKNOWN READ
Crash state:
ntlm_decode_type2_target
Curl_auth_decode_ntlm_type2_message
Curl_sasl_continue
```

## Which versions are affected by OSV-2021-696?

1 open source package ship an affected version, including curl.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `curl` | OSS-Fuzz | All versions | None |

## How do I fix OSV-2021-696?

No fix has been published for OSV-2021-696 yet. Limit exposure of the affected software until one is available.

## Is OSV-2021-696 being exploited?

There is no known exploitation of OSV-2021-696 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for OSV-2021-696 and fix it if it is affected.

What it is: OSV-2021-696 is a memory corruption vulnerability in curl, published on 28 Apr 2021. It can be exploited over the network, with no action from the victim.
Exploitation: There is no known exploitation of OSV-2021-696 in the wild and no public exploit code.

Affected packages and fixed versions:
- curl (OSS-Fuzz): affected all versions; no fix listed

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/OSV-2021-696/ (Markdown: https://insights.sbomify.com/OSV-2021-696/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/OSV-2021-696

---
From sbomify Insights: https://insights.sbomify.com/OSV-2021-696/
Summaries are generated and may contain mistakes; the official description above is the record.