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CVE-2021-21408

Access to restricted PHP code by dynamic static class access in smarty

Public exploit available. Not confirmed exploited in the wild yet. Fixed in 3.1.43.

CVSS 3.18.8HighEPSS percentile81st2.1% chance in 30 daysCISA KEVNot listedNo confirmed exploitation
Public exploit: 1 sourceFix3.1.43Upgrade to this build

Published Updated Sources: CVE.org, NVD, GitHub

NVD CVE.org

What to do

Find your product and version, then upgrade to the build on the right.

  • Smarty-php SmartyAffected: < 3.1.43Upgrade to: not statedAffected: >= 4.0.0, < 4.0.3Upgrade to: not statedStated by: CVE record
  • Packagist smarty/smartyAffected: < 3.1.43Upgrade to: 3.1.43Stated by: GitHub advisory

Versions as the sources state them. Full version matrix after sign-in

Check it yourselfA free OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Request an assessment to establish which checks fit your systems.

What it is

From the CVE record

Smarty is a template engine for PHP, facilitating the separation of presentation (HTML/CSS) from application logic. Prior to versions 3.1.43 and 4.0.3, template authors could run restricted static php methods. Users should upgrade to version 3.1.43 or 4.0.3 to receive a patch.

In plain language

No plain-language summary for this CVE yet.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS81st
Public exploit
CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

1 source with a proof of concept or module.

Exploit links, PoCs and Metasploit modules after sign-in
EPSS

2.1% chance of exploitation activity in the next 30 days, which ranks it in the 81st percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

The patch came 471 days before any public exploit.

  1. OpenVAS check added
  2. Public exploit / PoCsource: github-poc
  3. Patch availablerecord updated
  4. Publishedweakness classified, att&ck mapped

Affected products

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Scored 8.8 by NVD.

How it is reached

  • Attack Vector NetworkExploitable remotely over the network without any special conditions
  • Attack Complexity LowNo special conditions — the attack can be reliably reproduced
  • Privileges Required LowRequires basic user-level privileges
  • User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

  • Scope UnchangedImpact is limited to the vulnerable component itself

Impact if exploited

  • Confidentiality HighTotal information disclosure — all data in the component is compromised
  • Integrity HighTotal loss of integrity — attacker can modify any data in the component
  • Availability HighTotal denial of service — the component is completely unavailable

Weaknesses

ATT&CK techniques

Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.

Sources

References in the record

And 11 more references. See all after sign-in

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We'll flag the next CVE, public exploit or patch for Smarty, not every advisory. This one: public exploit.