CVE-2021-26120: Smarty/smarty PHP Code Injection By Malicious Vulnerability

CRITICAL
Advisory Identifier: GHSA-3rpf-5rqv-689q
Share
CVSS 9.8
CWE-94
Published
Advisory Summary

CVE-2021-26120 is a CRITICAL (CVSS 9.8) php code injection by malicious vulnerability (CWE-94: Improper Control of Generation of Code ('Code Injection')) affecting Smarty/smarty libraries in the Packagist ecosystem. The issue involves php code injection by malicious function name in smarty. Remediation is available by upgrading affected packages to version 3.1.39.

CVE-2021-26120 at a Glance

CVE Identifier CVE-2021-26120
GHSA Identifier GHSA-3rpf-5rqv-689q
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-94: Improper Control of Generation of Code ('Code Injection')
Affected Product Smarty/smarty
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 9.8

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: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 High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2021-26120

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

smarty/smarty fixed: 3.1.39 
Upgrade smarty/smarty to 3.1.39
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 smarty/smarty

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-26120, inspect your project dependencies for Smarty/smarty:

inspect dependencies for smarty/smarty

Analyze the terminal output to locate any version of Smarty/smarty in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.1.39), 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-94: Improper Control of Generation of Code ('Code Injection'), where the product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. In Smarty/smarty, 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

Template authors could inject php code by choosing a malicous {function} name. Sites that cannot fully trust template authors should update as soon as possible. Please upgrade to 3.1.39 or higher.

CVE-2021-26120 Affected Smarty/smarty Versions

1 component(s)
Fixed Versions:
3.1.39
Product / Package Ecosystem Affected Versions Fixed Version
smarty/smarty
 Packagist
< 3.1.39
3.1.39

References

GitHub Advisory / Wiki ADVISORY
https://github.com/smarty-php/smarty/security/advisories/GHSA-3rpf-5rqv-689q
NVD — CVE-2021-26120 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-26120
Security Fix Commit FIX COMMIT
https://github.com/smarty-php/smarty/commit/165f1bd4d2eec328cfeaca517a725b46001de838
Smarty/smarty Source Repository REPOSITORY
https://github.com/FriendsOfPHP/security-advisories/blob/master/smarty/smarty/CVE-2021-26120.yaml
Smarty/smarty Source Repository REPOSITORY
https://github.com/smarty-php/smarty
Smarty/smarty Source Repository REPOSITORY
https://github.com/smarty-php/smarty/blob/master/CHANGELOG.md
Smarty/smarty Source Repository REPOSITORY
https://github.com/smarty-php/smarty/blob/master/CHANGELOG.md#3139---2021-02-17
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2021/04/msg00004.html
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2021/04/msg00014.html
Smarty/smarty Security Information SECURITY
https://security.gentoo.org/glsa/202105-06
srcincite.io/blog/2021/02/18/sma... WEB
https://srcincite.io/blog/2021/02/18/smarty-template-engine-multiple-sandbox-escape-vulnerabilities.html
Smarty/smarty Security Information SECURITY
https://www.debian.org/security/2022/dsa-5151

Frequently Asked Questions

What is CVE-2021-26120?
CVE-2021-26120 is a security vulnerability in Smarty/smarty involving PHP Code Injection by malicious function name in smarty under CWE-94: Improper Control of Generation of Code ('Code Injection').
Which Smarty/smarty versions are affected?
Affected versions include releases prior to 3.1.39 across affected packages: smarty/smarty.
What version fixes CVE-2021-26120?
Upgrading to 3.1.39 (or the latest patched release for your respective branch) resolves the vulnerability.
Is smarty/smarty affected?
Yes, smarty/smarty is affected in releases prior to 3.1.39. Upgrade your dependency to 3.1.39 or later.
What is the CVSS score of CVE-2021-26120?
CVE-2021-26120 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2021-26120?
CVE-2021-26120 is classified under CWE-94: Improper Control of Generation of Code ('Code Injection') (The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.).
How can I check Packagist dependencies for CVE-2021-26120?
Run the dependency tree command: 'inspect dependencies for smarty/smarty'. 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-3rpf-5rqv-689q",
  "modified" : "2022-05-03T03:01:58Z",
  "published" : "2021-02-26T19:53:24Z",
  "aliases" : [ "CVE-2021-26120" ],
  "summary" : "PHP Code Injection by malicious function name in smarty",
  "details" : "Template authors could inject php code by choosing a malicous {function} name. Sites that cannot fully trust template authors should update as soon as possible. Please upgrade to 3.1.39 or higher.\n",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "smarty/smarty"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.1.39"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/smarty-php/smarty/security/advisories/GHSA-3rpf-5rqv-689q"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-26120"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/smarty-php/smarty/commit/165f1bd4d2eec328cfeaca517a725b46001de838"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/FriendsOfPHP/security-advisories/blob/master/smarty/smarty/CVE-2021-26120.yaml"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/smarty-php/smarty"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/smarty-php/smarty/blob/master/CHANGELOG.md"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/smarty-php/smarty/blob/master/CHANGELOG.md#3139---2021-02-17"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2021/04/msg00004.html"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2021/04/msg00014.html"
  }, {
    "type" : "WEB",
    "url" : "https://security.gentoo.org/glsa/202105-06"
  }, {
    "type" : "WEB",
    "url" : "https://srcincite.io/blog/2021/02/18/smarty-template-engine-multiple-sandbox-escape-vulnerabilities.html"
  }, {
    "type" : "WEB",
    "url" : "https://www.debian.org/security/2022/dsa-5151"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-94" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-02-26T19:52:58Z",
    "nvd_published_at" : "2021-02-22T02:15:00Z"
  }
}