# OSV-2020-1017: Heap-buffer-overflow in decode_bit_string

> A heap-buffer-overflow in the ASN.1 bit string decoder allows attackers to cause crashes or potentially execute code via crafted input.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Not stated
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 22 Jul 2020

## What is OSV-2020-1017?

OSV-2020-1017 is a memory corruption vulnerability in opensc, published on 22 Jul 2020. 

### Official description

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=16614

```
Crash type: Heap-buffer-overflow READ 1
Crash state:
decode_bit_string
sc_asn1_print_bit_string
print_tags_recursive
```

## Which versions are affected by OSV-2020-1017?

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


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

## How do I fix OSV-2020-1017?

No fix has been published for OSV-2020-1017 yet. Limit exposure of the affected software until one is available.

## Is OSV-2020-1017 being exploited?

There is no known exploitation of OSV-2020-1017 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for OSV-2020-1017 and fix it if it is affected.

What it is: OSV-2020-1017 is a memory corruption vulnerability in opensc, published on 22 Jul 2020. 
Exploitation: There is no known exploitation of OSV-2020-1017 in the wild and no public exploit code.

Affected packages and fixed versions:
- opensc (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-2020-1017/ (Markdown: https://insights.sbomify.com/OSV-2020-1017/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/OSV-2020-1017

---
From sbomify Insights: https://insights.sbomify.com/OSV-2020-1017/
Summaries are generated and may contain mistakes; the official description above is the record.