CVE-2021-45720: Lru Use After Free Vulnerability

HIGH
Advisory Identifier: GHSA-v362-2895-h9r2
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CVSS 7.5
CWE-416
Published
Advisory Summary

CVE-2021-45720 is a HIGH (CVSS 7.5) use after free vulnerability (CWE-416: Use After Free) affecting Lru libraries in the crates.io ecosystem. The issue involves use after free in lru. Remediation is available by upgrading affected packages to version 0.7.1.

CVE-2021-45720 at a Glance

CVE Identifier CVE-2021-45720
GHSA Identifier GHSA-v362-2895-h9r2
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-416: Use After Free
Affected Product Lru
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 7.5

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:N/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 None (I:N)
Availability High (A:H)

How to Fix CVE-2021-45720

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

lru fixed: 0.7.1 
Upgrade lru to 0.7.1
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 lru

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-45720, inspect your project dependencies for Lru:

inspect dependencies for lru

Analyze the terminal output to locate any version of Lru in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.7.1), 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 any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.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 Lru, 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

Lru crate has two functions for getting an iterator. Both iterators give references to key and value. Calling specific functions, like pop(), will remove and free the value, and but it's still possible to access the reference of value which is already dropped causing use after free.

CVE-2021-45720 Affected Lru Versions

1 component(s)
Fixed Versions:
0.7.1
Product / Package Ecosystem Affected Versions Fixed Version
lru
 crates.io
< 0.7.1
0.7.1

References

NVD — CVE-2021-45720 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-45720
Lru Source Repository REPOSITORY
https://github.com/jeromefroe/lru-rs/issues/120
Lru Source Repository REPOSITORY
https://github.com/jeromefroe/lru-rs.git
raw.githubusercontent.com/rustsec/advisory-db... WEB
https://raw.githubusercontent.com/rustsec/advisory-db/main/crates/lru/RUSTSEC-2021-0130.md
rustsec.org/advisories/rustsec-... WEB
https://rustsec.org/advisories/RUSTSEC-2021-0130.html

Frequently Asked Questions

What is CVE-2021-45720?
CVE-2021-45720 is a security vulnerability in Lru involving Use After Free in lru under CWE-416: Use After Free.
Which Lru versions are affected?
Affected versions include releases prior to 0.7.1 across affected packages: lru.
What version fixes CVE-2021-45720?
Upgrading to 0.7.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is lru affected?
Yes, lru is affected in releases prior to 0.7.1. Upgrade your dependency to 0.7.1 or later.
What is the CVSS score of CVE-2021-45720?
CVE-2021-45720 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2021-45720?
CVE-2021-45720 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-2021-45720?
Run the dependency tree command: 'inspect dependencies for lru'. 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-v362-2895-h9r2",
  "modified" : "2023-06-13T18:38:43Z",
  "published" : "2022-01-07T22:37:01Z",
  "aliases" : [ "CVE-2021-45720" ],
  "summary" : "Use After Free in lru",
  "details" : "Lru crate has two functions for getting an iterator. Both iterators give references to key and value. Calling specific functions, like pop(), will remove and free the value, and but it's still possible to access the reference of value which is already dropped causing use after free.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "lru"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.7.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-45720"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/jeromefroe/lru-rs/issues/120"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/jeromefroe/lru-rs.git"
  }, {
    "type" : "WEB",
    "url" : "https://raw.githubusercontent.com/rustsec/advisory-db/main/crates/lru/RUSTSEC-2021-0130.md"
  }, {
    "type" : "WEB",
    "url" : "https://rustsec.org/advisories/RUSTSEC-2021-0130.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-416" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-01-07T20:44:44Z",
    "nvd_published_at" : "2021-12-26T22:15:00Z"
  }
}