# OSV-2017-83: Heap-buffer-overflow in idn2_lookup_u8

> A heap-buffer-overflow in libidn2 allows attackers to cause denial of service or potentially execute code via crafted IDN inputs.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 13 Jan 2021

## What is OSV-2017-83?

OSV-2017-83 is a memory corruption vulnerability in libpsl, published on 13 Jan 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2262

```
Crash type: Heap-buffer-overflow READ 4
Crash state:
idn2_lookup_u8
_psl_idna_toASCII
_add_punycode_if_needed
```

## Which versions are affected by OSV-2017-83?

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


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

## How do I fix OSV-2017-83?

No fix has been published for OSV-2017-83 yet. Limit exposure of the affected software until one is available.

## Is OSV-2017-83 being exploited?

There is no known exploitation of OSV-2017-83 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for OSV-2017-83 and fix it if it is affected.

What it is: OSV-2017-83 is a memory corruption vulnerability in libpsl, published on 13 Jan 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of OSV-2017-83 in the wild and no public exploit code.

Affected packages and fixed versions:
- libpsl (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-2017-83/ (Markdown: https://insights.sbomify.com/OSV-2017-83/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/OSV-2017-83

---
From sbomify Insights: https://insights.sbomify.com/OSV-2017-83/
Summaries are generated and may contain mistakes; the official description above is the record.