CVE-2020-35898: Actix utils Use After Free Vulnerability

CRITICAL
Advisory Identifier: GHSA-hhw2-pqhf-vmx2
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CVSS 9.1
CWE-416
Published
Advisory Summary

CVE-2020-35898 is a CRITICAL (CVSS 9.1) use after free vulnerability (CWE-416: Use After Free) affecting Actix utils libraries in the crates.io ecosystem. The issue involves use after free in actix-utils. Remediation is available by upgrading affected packages to version 2.0.0.

CVE-2020-35898 at a Glance

CVE Identifier CVE-2020-35898
GHSA Identifier GHSA-hhw2-pqhf-vmx2
Severity CRITICAL
CVSS v3.1 Base Score 9.1
CWE Classification CWE-416: Use After Free
Affected Product Actix utils
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 9.1

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

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

How to Fix CVE-2020-35898

To remediate this vulnerability, upgrade all affected Actix utils 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-utils fixed: 2.0.0 
Upgrade actix-utils to 2.0.0
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-utils

How to Check if You Are Affected

To determine whether your application is affected by CVE-2020-35898, inspect your project dependencies for Actix utils:

inspect dependencies for actix-utils

Analyze the terminal output to locate any version of Actix utils in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.0.0), 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 utils, 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-utils crate before 2.0.0 for Rust. The Cell implementation allows obtaining more than one mutable reference to the same data.

CVE-2020-35898 Affected Actix utils Versions

1 component(s)
Fixed Versions:
2.0.0
Product / Package Ecosystem Affected Versions Fixed Version
actix-utils
 crates.io
< 2.0.0
2.0.0

References

NVD — CVE-2020-35898 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-35898
Actix utils Source Repository REPOSITORY
https://github.com/actix/actix-net/issues/160
Security Fix Commit FIX COMMIT
https://github.com/actix/actix-net/commit/0dca1a705ad1ff4885b3491ecb809a808e1de66c
Actix utils Source Repository REPOSITORY
https://github.com/actix/actix-net
rustsec.org/advisories/rustsec-... WEB
https://rustsec.org/advisories/RUSTSEC-2020-0045.html

Frequently Asked Questions

What is CVE-2020-35898?
CVE-2020-35898 is a security vulnerability in Actix utils involving Use after free in actix-utils under CWE-416: Use After Free.
Which Actix utils versions are affected?
Affected versions include releases prior to 2.0.0 across affected packages: actix-utils.
What version fixes CVE-2020-35898?
Upgrading to 2.0.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is actix-utils affected?
Yes, actix-utils is affected in releases prior to 2.0.0. Upgrade your dependency to 2.0.0 or later.
What is the CVSS score of CVE-2020-35898?
CVE-2020-35898 has a CVSS v3.1 base score of 9.1 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H.
What CWE is associated with CVE-2020-35898?
CVE-2020-35898 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-2020-35898?
Run the dependency tree command: 'inspect dependencies for actix-utils'. 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-hhw2-pqhf-vmx2",
  "modified" : "2025-05-23T18:29:56Z",
  "published" : "2021-08-25T20:49:09Z",
  "aliases" : [ "CVE-2020-35898" ],
  "summary" : "Use after free in actix-utils",
  "details" : "An issue was discovered in the actix-utils crate before 2.0.0 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:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "actix-utils"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.0.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-35898"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/actix/actix-net/issues/160"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/actix/actix-net/commit/0dca1a705ad1ff4885b3491ecb809a808e1de66c"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/actix/actix-net"
  }, {
    "type" : "WEB",
    "url" : "https://rustsec.org/advisories/RUSTSEC-2020-0045.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-416" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-08-19T20:53:53Z",
    "nvd_published_at" : null
  }
}