CVE-2020-35899: Actix service Use After Free Vulnerability

MODERATE
Advisory Identifier: GHSA-whc7-5p35-4ww2
Share
CVSS 5.5
CWE-416
Published
Advisory Summary

CVE-2020-35899 is a MODERATE (CVSS 5.5) use after free vulnerability (CWE-416: Use After Free) affecting Actix service libraries in the crates.io ecosystem. The issue involves use after free in actix-service. Remediation is available by upgrading affected packages to version 1.0.6.

CVE-2020-35899 at a Glance

CVE Identifier CVE-2020-35899
GHSA Identifier GHSA-whc7-5p35-4ww2
Severity MODERATE
CVSS v3.1 Base Score 5.5
CWE Classification CWE-416: Use After Free
Affected Product Actix service
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 5.5

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

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

How to Fix CVE-2020-35899

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

actix-service fixed: 1.0.6 
Upgrade actix-service to 1.0.6
Verify Direct and Transitive Dependencies

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

inspect dependencies for actix-service

How to Check if You Are Affected

To determine whether your application is affected by CVE-2020-35899, inspect your project dependencies for Actix service:

inspect dependencies for actix-service

Analyze the terminal output to locate any version of Actix service in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.0.6), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-416: Use After Free, where the product reuses or references memory after it has been freed. at some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer. In Actix service, 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

An issue was discovered in the actix-service crate before 1.0.6 for Rust. The Cell implementation allows obtaining more than one mutable reference to the same data.

CVE-2020-35899 Affected Actix service Versions

1 component(s)
Fixed Versions:
1.0.6
Product / Package Ecosystem Affected Versions Fixed Version
actix-service
 crates.io
< 1.0.6
1.0.6

References

NVD — CVE-2020-35899 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-35899
Actix service Source Repository REPOSITORY
https://github.com/actix/actix-net/pull/158
Security Fix Commit FIX COMMIT
https://github.com/actix/actix-net/commit/a67e38b4a07c92a3c81fa833f9eb1e91e74e39b7
Actix service Source Repository REPOSITORY
https://github.com/actix/actix-net
rustsec.org/advisories/rustsec-... WEB
https://rustsec.org/advisories/RUSTSEC-2020-0046.html

Frequently Asked Questions

What is CVE-2020-35899?
CVE-2020-35899 is a security vulnerability in Actix service involving Use after free in actix-service under CWE-416: Use After Free.
Which Actix service versions are affected?
Affected versions include releases prior to 1.0.6 across affected packages: actix-service.
What version fixes CVE-2020-35899?
Upgrading to 1.0.6 (or the latest patched release for your respective branch) resolves the vulnerability.
Is actix-service affected?
Yes, actix-service is affected in releases prior to 1.0.6. Upgrade your dependency to 1.0.6 or later.
What is the CVSS score of CVE-2020-35899?
CVE-2020-35899 has a CVSS v3.1 base score of 5.5 (MODERATE) with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2020-35899?
CVE-2020-35899 is classified under CWE-416: Use After Free (The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.).
How can I check crates.io dependencies for CVE-2020-35899?
Run the dependency tree command: 'inspect dependencies for actix-service'. 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-whc7-5p35-4ww2",
  "modified" : "2025-05-23T18:31:05Z",
  "published" : "2021-08-25T20:49:06Z",
  "aliases" : [ "CVE-2020-35899" ],
  "summary" : "Use after free in actix-service",
  "details" : "An issue was discovered in the actix-service crate before 1.0.6 for Rust. The Cell implementation allows obtaining more than one mutable reference to the same data.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "actix-service"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.0.6"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-35899"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/actix/actix-net/pull/158"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/actix/actix-net/commit/a67e38b4a07c92a3c81fa833f9eb1e91e74e39b7"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/actix/actix-net"
  }, {
    "type" : "WEB",
    "url" : "https://rustsec.org/advisories/RUSTSEC-2020-0046.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-416" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-08-19T20:54:21Z",
    "nvd_published_at" : null
  }
}