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CVE-2021-29454

29
FAUCET Score

CVE-2021-29454 is a high-severity vulnerability affecting Smarty, a PHP template engine, prior to versions 3.1.42 and 4.0.2, as well as various Debian and Fedora distributions. It allows authenticated attackers to execute arbitrary PHP code by injecting malicious math strings into the math function. With a CVSS score of 8.8, this vulnerability presents a significant risk due to its low attack complexity and potential for complete compromise of confidentiality, integrity, and availability. While no public exploits or active exploitation have been observed, and community discussion is minimal, organizations using affected Smarty versions should prioritize upgrading to mitigate this critical risk.

Impacted Technologies

VendorProductVersion(s)CPE
< 3.1.42CPE matchmatch criteria
cpe:2.3:a:smarty:smarty:*:*:*:*:*:*:*:*
>= 4.0.0, < 4.0.2CPE 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

8.1HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
5.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.93%
Probability of exploitation in next 30 days
EPSS Percentile
77.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0193 is in the 76th percentile among its peer group of 17,823 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: 3.1.42
composerpatch availablevia ghsa
Product: smarty/smartyFixed in: 4.0.2
github_advisorypatch availablevia nvd_reference
View patch

Vendor Advisories (1)

composerGHSA-29gp-2c3m-3j6mhigh

Sandbox Escape by math function in smarty

Jan 12, 2022

References

github.com / smarty-php/smarty/commit/215d81a9fa3cd63d82fb3ab56ecaf97cf1e7db71
PatchThird Party Advisory
github.com / smarty-php/smarty/releases/tag/v3.1.42
Release NotesThird Party Advisory
github.com / smarty-php/smarty/releases/tag/v4.0.2
Release NotesThird Party Advisory
github.com / smarty-php/smarty/security/advisories/GHSA-29gp-2c3m-3j6m
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
packagist.org / packages/smarty/smarty
ProductThird Party Advisory
security.gentoo.org / glsa/202209-09
Third Party Advisory
debian.org / security/2022/dsa-5151
Third Party Advisory
smarty.net / docs/en/language.function.math.tpl
Vendor Advisory