# CVE-2026-3989: CVE-2026-3989

> An attacker can execute arbitrary code on the host by providing a malicious pickle file to the SGLang replay_request_dump.py script.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 12 Mar 2026
- **Updated:** 7 Apr 2026
- **Also known as:** GHSA-hvwj-8w5g-28rg, PYSEC-2026-3063

## What is CVE-2026-3989?

CVE-2026-3989 is a high-severity unsafe deserialization vulnerability in SGLang, published on 12 Mar 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

SGLangs `replay_request_dump.py` contains an insecure pickle.load() without validation and proper deserialization. An attacker can take advantage of this by providing a malicious .pkl file, which will execute the attackers code on the device running the script.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2026-3989?

3 open source packages ship an affected version, including sglang. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `sglang` | PyPI | All versions | 0.5.10 |
| `sglang` | PyPI | All versions | 0.5.10 |
| `sglang` | PyPI | All versions | 0.5.10 |

Products: Lmsys Sglang.

## How do I fix CVE-2026-3989?

Upgrade sglang to 0.5.10 or later.

## Is CVE-2026-3989 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3989 exists.

## Other vulnerabilities in SGLang

- [CVE-2026-15969](https://insights.sbomify.com/CVE-2026-15969/): CVE-2026-15969 (critical 9.8)
- [CVE-2026-15971](https://insights.sbomify.com/CVE-2026-15971/): CVE-2026-15971 (critical 9.8)
- [CVE-2026-15976](https://insights.sbomify.com/CVE-2026-15976/): CVE-2026-15976 (critical 9.8)
- [CVE-2026-7301](https://insights.sbomify.com/CVE-2026-7301/): CVE-2026-7301 (critical 9.8)
- [CVE-2026-7304](https://insights.sbomify.com/CVE-2026-7304/): CVE-2026-7304 (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-3989 and fix it if it is affected.

What it is: CVE-2026-3989 is a high-severity unsafe deserialization vulnerability in SGLang, published on 12 Mar 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3989 exists.

Affected packages and fixed versions:
- sglang (PyPI): affected all versions; fixed in 0.5.10
- sglang (PyPI): affected all versions; fixed in 0.5.10
- sglang (PyPI): affected all versions; fixed in 0.5.10

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-2026-3989/ (Markdown: https://insights.sbomify.com/CVE-2026-3989/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-3989
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-3989
- OSV: https://osv.dev/vulnerability/CVE-2026-3989

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-3989/
Summaries are generated and may contain mistakes; the official description above is the record.