CVE-2021-26953: Postscript Read On Uninitialized Buffer Vulnerability

HIGH
Advisory Identifier: GHSA-fhvc-gp6c-h2wx
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CVSS 7.5
CWE-908
Published
Advisory Summary

CVE-2021-26953 is a HIGH (CVSS 7.5) read on uninitialized buffer vulnerability (CWE-908: Use of Uninitialized Resource) affecting Postscript libraries in the crates.io ecosystem. The issue involves read on uninitialized buffer in postscript. Remediation is available by upgrading affected packages to version 0.14.0.

CVE-2021-26953 at a Glance

CVE Identifier CVE-2021-26953
GHSA Identifier GHSA-fhvc-gp6c-h2wx
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-908: Use of Uninitialized Resource
Affected Product Postscript
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:H/I:N/A:N).

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 High (C:H)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2021-26953

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

postscript fixed: 0.14.0 
Upgrade postscript to 0.14.0
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 postscript

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-26953, inspect your project dependencies for Postscript:

inspect dependencies for postscript

Analyze the terminal output to locate any version of Postscript in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.14.0), 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-908: Use of Uninitialized Resource, where the product uses or accesses a resource that has not been initialized. In Postscript, 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

Affected versions of this crate passes an uninitialized buffer to a user-provided Read implementation. Arbitrary Read implementations can read from the uninitialized buffer (memory exposure) and also can return incorrect number of bytes written to the buffer. Reading from uninitialized memory produces undefined values that can quickly invoke undefined behavior. This flaw was fixed in commit `8026286` by zero-initializing the buffer before handing to a user-provided Read.

CVE-2021-26953 Affected Postscript Versions

1 component(s)
Fixed Versions:
0.14.0
Product / Package Ecosystem Affected Versions Fixed Version
postscript
 crates.io
< 0.14.0
0.14.0

References

NVD — CVE-2021-26953 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-26953
Postscript Source Repository REPOSITORY
https://github.com/bodoni/postscript/issues/1
Security Fix Commit FIX COMMIT
https://github.com/bodoni/postscript/commit/8026286
Postscript Source Repository REPOSITORY
https://github.com/bodoni/postscript
rustsec.org/advisories/rustsec-... WEB
https://rustsec.org/advisories/RUSTSEC-2021-0017.html

Frequently Asked Questions

What is CVE-2021-26953?
CVE-2021-26953 is a security vulnerability in Postscript involving Read on uninitialized buffer in postscript under CWE-908: Use of Uninitialized Resource.
Which Postscript versions are affected?
Affected versions include releases prior to 0.14.0 across affected packages: postscript.
What version fixes CVE-2021-26953?
Upgrading to 0.14.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is postscript affected?
Yes, postscript is affected in releases prior to 0.14.0. Upgrade your dependency to 0.14.0 or later.
What is the CVSS score of CVE-2021-26953?
CVE-2021-26953 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:H/I:N/A:N.
What CWE is associated with CVE-2021-26953?
CVE-2021-26953 is classified under CWE-908: Use of Uninitialized Resource (The product uses or accesses a resource that has not been initialized.).
How can I check crates.io dependencies for CVE-2021-26953?
Run the dependency tree command: 'inspect dependencies for postscript'. 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-fhvc-gp6c-h2wx",
  "modified" : "2023-06-13T20:33:52Z",
  "published" : "2021-08-25T20:52:23Z",
  "aliases" : [ "CVE-2021-26953" ],
  "summary" : "Read on uninitialized buffer in postscript",
  "details" : "Affected versions of this crate passes an uninitialized buffer to a user-provided Read implementation.\n\nArbitrary Read implementations can read from the uninitialized buffer (memory exposure) and also can return incorrect number of bytes written to the buffer. Reading from uninitialized memory produces undefined values that can quickly invoke undefined behavior.\n\nThis flaw was fixed in commit `8026286` by zero-initializing the buffer before handing to a user-provided Read.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "postscript"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.14.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-26953"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/bodoni/postscript/issues/1"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/bodoni/postscript/commit/8026286"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/bodoni/postscript"
  }, {
    "type" : "WEB",
    "url" : "https://rustsec.org/advisories/RUSTSEC-2021-0017.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-908" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-08-19T17:35:31Z",
    "nvd_published_at" : null
  }
}