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CVE-2021-21408

30
FAUCET Score

CVE-2021-21408 is a high-severity vulnerability affecting Smarty, a PHP template engine, specifically versions prior to 3.1.43 and 4.0.3. It allows authenticated template authors to execute restricted static PHP methods, impacting confidentiality, integrity, and availability of affected systems, including various Debian and Fedora distributions. With a CVSS score of 8.8, this vulnerability is easily exploitable over the network with low attack complexity. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 3.1.43CPE matchmatch criteria
cpe:2.3:a:smarty:smarty:*:*:*:*:*:*:*:*
>= 4.0.0, < 4.0.3CPE matchmatch criteria
cpe:2.3:a:smarty:smarty:*:*:*:*:*:*:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
11.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.8HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.22%
Probability of exploitation in next 30 days
EPSS Percentile
80.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0222 is in the 79th percentile among its peer group of 17,844 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.3 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (3)

composerpatch availablevia ghsa
Product: smarty/smartyFixed in: 3.1.43
composerpatch availablevia ghsa
Product: smarty/smartyFixed in: 4.0.3
github_advisorypatch availablevia nvd_reference
View patch

Vendor Advisories (1)

composerGHSA-4h9c-v5vg-5m6mhigh

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

Jan 12, 2022

References

github.com / smarty-php/smarty/commit/19ae410bf56007a5ef24441cdc6414619cfaf664
PatchThird Party Advisory
github.com / smarty-php/smarty/releases/tag/v3.1.43
Release NotesThird Party Advisory
github.com / smarty-php/smarty/releases/tag/v4.0.3
Release NotesThird Party Advisory
github.com / smarty-php/smarty/security/advisories/GHSA-4h9c-v5vg-5m6m
Third Party Advisory
lists.debian.org / debian-lts-announce/2022/05/msg00005.html
Mailing ListThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/BRAJVDRGCIY5UZ2PQHKDTT7RMKG6WJQQ
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/L777JIBIWJV34HS7LXPIDWASG7TT4LNI
security.gentoo.org / glsa/202209-09
Third Party Advisory
debian.org / security/2022/dsa-5151
Third Party Advisory