# OSV-2020-2117: Heap-buffer-overflow in flb_msgpack_gelf_value_ext

> A heap-buffer-overflow in Fluent Bit's GELF message pack processing allows attackers to cause denial of service or potentially execute code via crafted input.

- **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:** 2 Nov 2020

## What is OSV-2020-2117?

OSV-2020-2117 is a memory corruption vulnerability in fluent-bit, published on 2 Nov 2020. 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=26851

```
Crash type: Heap-buffer-overflow READ 1
Crash state:
flb_msgpack_gelf_value_ext
flb_msgpack_to_gelf
flb_msgpack_raw_to_gelf
```

## Which versions are affected by OSV-2020-2117?

1 open source package ship an affected version, including fluent-bit.


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

## How do I fix OSV-2020-2117?

No fix has been published for OSV-2020-2117 yet. Limit exposure of the affected software until one is available.

## Is OSV-2020-2117 being exploited?

There is no known exploitation of OSV-2020-2117 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for OSV-2020-2117 and fix it if it is affected.

What it is: OSV-2020-2117 is a memory corruption vulnerability in fluent-bit, published on 2 Nov 2020. 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-2020-2117 in the wild and no public exploit code.

Affected packages and fixed versions:
- fluent-bit (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-2020-2117/ (Markdown: https://insights.sbomify.com/OSV-2020-2117/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/OSV-2020-2117

---
From sbomify Insights: https://insights.sbomify.com/OSV-2020-2117/
Summaries are generated and may contain mistakes; the official description above is the record.