CVE-2026-3989: Sglang SGLangs `replay_request_dump.py` Contains An Insecure Vulnerability

HIGH
Advisory Identifier: GHSA-hvwj-8w5g-28rg
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CVSS 7.8
CWE-502
Published
Advisory Summary

CVE-2026-3989 is a HIGH (CVSS 7.8) sglangs `replay_request_dump.py` contains an insecure vulnerability (CWE-502: Deserialization of Untrusted Data) affecting Sglang libraries in the PyPI ecosystem. The issue involves sglangs `replay_request_dump.py` contains an insecure pickle.load() without validation and proper deserialization. Remediation is available by upgrading affected packages to version 0.5.10.

CVE-2026-3989 at a Glance

CVE Identifier CVE-2026-3989
GHSA Identifier GHSA-hvwj-8w5g-28rg
Severity HIGH
CVSS v3.1 Base Score 7.8
CWE Classification CWE-502: Deserialization of Untrusted Data
Affected Product Sglang
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 7.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H).

Attack Vector Local (AV:L)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-3989

To remediate this vulnerability, upgrade all affected Sglang dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

sglang fixed: 0.5.10 
pip install sglang>=0.5.10
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show sglang

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-3989, inspect your installed packages using pip:

pip show sglang

Analyze the terminal output to locate any version of Sglang in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.5.10), your application is affected.

Note: The pip show sglang command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-502: Deserialization of Untrusted Data, where the product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid. In Sglang, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

CVE-2026-3989 Affected Sglang Versions

1 component(s)
Fixed Versions:
0.5.10
Product / Package Ecosystem Affected Versions Fixed Version
sglang
pypi/sglang
PyPI
< 0.5.10
0.5.10

References

NVD — CVE-2026-3989 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-3989
Sglang Source Repository REPOSITORY
https://github.com/sgl-project/sglang/pull/20904
Sglang Source Repository REPOSITORY
https://github.com/sgl-project/sglang
Sglang Source Repository REPOSITORY
https://github.com/sgl-project/sglang/blob/main/scripts/playground/replay_request_dump.py
Sglang Release RELEASE
https://github.com/sgl-project/sglang/releases/tag/v0.5.10
Sglang Security Information SECURITY
https://orca.security/resources/blog/sglang-llm-framework-rce-vulnerabilities

Frequently Asked Questions

What is CVE-2026-3989?
CVE-2026-3989 is a security vulnerability in Sglang involving SGLangs `replay_request_dump.py` contains an insecure pickle.load() without validation and proper deserialization under CWE-502: Deserialization of Untrusted Data.
Which Sglang versions are affected?
Affected versions include releases prior to 0.5.10 across affected packages: sglang.
What version fixes CVE-2026-3989?
Upgrading to 0.5.10 (or the latest patched release for your respective branch) resolves the vulnerability.
Is sglang affected?
Yes, sglang is affected in releases prior to 0.5.10. Upgrade your dependency to 0.5.10 or later.
What is the CVSS score of CVE-2026-3989?
CVE-2026-3989 has a CVSS v3.1 base score of 7.8 (HIGH) with vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-3989?
CVE-2026-3989 is classified under CWE-502: Deserialization of Untrusted Data (The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.).
How can I check PyPI dependencies for CVE-2026-3989?
Run the dependency tree command: 'pip show sglang'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-hvwj-8w5g-28rg",
  "modified" : "2026-04-07T22:14:04Z",
  "published" : "2026-03-12T12:30:29Z",
  "aliases" : [ "CVE-2026-3989" ],
  "summary" : "SGLangs `replay_request_dump.py` contains an insecure pickle.load() without validation and proper deserialization",
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "sglang"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.5.10"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.5.9"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-3989"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/sgl-project/sglang/pull/20904"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/sgl-project/sglang"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/sgl-project/sglang/blob/main/scripts/playground/replay_request_dump.py"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/sgl-project/sglang/releases/tag/v0.5.10"
  }, {
    "type" : "WEB",
    "url" : "https://orca.security/resources/blog/sglang-llm-framework-rce-vulnerabilities"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-502" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-12T17:39:04Z",
    "nvd_published_at" : "2026-03-12T12:15:59Z"
  }
}