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Not in CISA KEV
HIGH severity

CVE-2021-26119 — smarty

HIGH

CVE-2021-26119 is a high-severity (CVSS 7.5) vulnerability in smarty/smarty. 1 public exploit reference exists, so weaponization risk is real. A fix is available for smarty/smarty — see the affected versions and patch details below.

Sandbox escape through template_object in smarty

Also known asGHSA-w5hr-jm4j-9jvq
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
1 known
Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
9.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs95th percentile — riskier than 95% of all scored CVEsHighest risk
0.00%26.2%52.4%78.6%62.6%9.4%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-26119 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🐘smarty/smarty

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

Sandbox protection could be bypassed through access to an internal Smarty object that should have been blocked. Sites that rely on Smarty Security features should upgrade as soon as possible. Please upgrade to 3.1.39 or higher.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐘Packagistsmarty/smartyall versions3.1.39composer require smarty/smarty:^3.1.39

Affected Products

2 products · 4 configurations
OS
debian linuxdebian
3 versions
9.010.011.0
Application
smartysmarty
< 3.1.39
range
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Smarty before 3.1.39 allows a Sandbox Escape because $smarty.template_ob…

github.comGithubFeb 2021

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for smarty/smarty, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update smarty/smarty to 3.1.39 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-26119 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

Sandbox protection could be bypassed through access to an internal Smarty object that should have been blocked. Sites that rely on [Smarty Security features](https://www.smarty.net/docs/en/advanced.features.tpl) should upgrade as soon as possible. Please upgrade to 3.1.39 or higher.
O3 Security · Impact-Aware SCA

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CVE-2021-26119: smarty — Fixed in 3.1.39