# CVE-2021-31635: jFinal Server-Side Template Injection vulnerability

> Remote attackers can execute arbitrary code via Server-Side Template Injection in the jFinal Java web framework.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 26 Jun 2023
- **Updated:** 5 Dec 2024
- **Also known as:** GHSA-cgmm-c2m9-ff7r

## What is CVE-2021-31635?

CVE-2021-31635 is a critical code injection vulnerability in n/a, published on 26 Jun 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Server-Side Template Injection (SSTI) vulnerability in jFinal v.4.9.08 allows a remote attacker to execute arbitrary code via the template function.

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

## Which versions are affected by CVE-2021-31635?

2 open source packages ship an affected version, including com.jfinal:jfinal. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `com.jfinal:jfinal` | Maven | All versions to 4.9.08 | None |
| `com.jfinal:jfinal` | Maven | All versions to 4.9.08 | None |

Products: Jfinal Jfinal.

## How do I fix CVE-2021-31635?

No fix has been published for CVE-2021-31635 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-31635 being exploited?

There is no known exploitation of CVE-2021-31635 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2021-31649](https://insights.sbomify.com/CVE-2021-31649/): JFinal Java Deserialization Vulnerability (critical 9.8)
- [CVE-2019-17352](https://insights.sbomify.com/CVE-2019-17352/): JFinal file validation vulnerability (high 7.5)
- [CVE-2021-33348](https://insights.sbomify.com/CVE-2021-33348/): Cross-site scripting in jfinal (medium 6.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-31635 and fix it if it is affected.

What it is: CVE-2021-31635 is a critical code injection vulnerability in n/a, published on 26 Jun 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-31635 in the wild and no public exploit code.

Affected packages and fixed versions:
- com.jfinal:jfinal (Maven): affected all versions up to 4.9.08; no fix listed
- com.jfinal:jfinal (Maven): affected all versions up to 4.9.08; no fix listed

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-2021-31635/ (Markdown: https://insights.sbomify.com/CVE-2021-31635/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-31635
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-31635
- OSV: https://osv.dev/vulnerability/CVE-2021-31635

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-31635/
Summaries are generated and may contain mistakes; the official description above is the record.