# CVE-2026-82531: Smarty before 4.5.8 and 5.x before 5.8.5 PHP Code Injection via extends: Inheritance Cache

> Attackers can execute arbitrary PHP code by injecting forged nocache markers into template inheritance caches, affecting applications using the Smarty library.

- **Severity:** Critical 9.2 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 6 Oct 2026
- **Updated:** 6 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-82531, GHSA-3w63-v7pm-cq9x, UBUNTU-CVE-2026-82531

## What is CVE-2026-82531?

CVE-2026-82531 is a critical code injection vulnerability in smarty-php smarty, published on 6 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Smarty before 4.5.8 and 5.x before 5.8.5 contains a code injection vulnerability where the top-level nocache_hash is never restored during extends:/multi-component template inheritance, leaving it null. Attackers can supply assigned data containing a forged SmartyNocache marker that is copied verbatim into the regenerated PHP cache file, executing arbitrary PHP on include for remote code execution.

Weakness: CWE-94 (Improper Control of Generation of Code)

## Which versions are affected by CVE-2026-82531?


## How do I fix CVE-2026-82531?

No fix has been published for CVE-2026-82531 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-82531 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-82531 exists.

Public exploit code:

- Smarty is vulnerable to code injection through template inheritance. Crafted assigned data can inject a forged SmartyNocache marker into regenerated PHP cache files, potentially allowing attackers to execute arbitrary PHP code. The issue affects Smarty 4.5.7 and earlier, and 5.8.4 and earlier. (github_poc): https://github.com/murrez/CVE-2026-82531

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-82531 and fix it if it is affected.

What it is: CVE-2026-82531 is a critical code injection vulnerability in smarty-php smarty, published on 6 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-82531 exists.

Affected product: smarty-php smarty. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-82531/ (Markdown: https://insights.sbomify.com/CVE-2026-82531/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-82531
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-82531
- OSV: https://osv.dev/vulnerability/CVE-2026-82531

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-82531/
Summaries are generated and may contain mistakes; the official description above is the record.