# CVE-2021-28170: Improper Input Validation in Jakarta Expression Language

> Attackers can execute arbitrary code by exploiting a parser bug in the Jakarta Expression Language implementation that allows invalid expressions to be evaluated.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 May 2021
- **Updated:** 3 Aug 2024
- **Also known as:** CLSA-2025-1752537768, DEBIAN-CVE-2021-28170, GHSA-v6w3-2prq-h95f, UBUNTU-CVE-2021-28170

## What is CVE-2021-28170?

CVE-2021-28170 is a medium-severity code injection vulnerability in Oracle Communications Cloud Native Core Policy, published on 26 May 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Jakarta Expression Language implementation 3.0.3 and earlier, a bug in the ELParserTokenManager enables invalid EL expressions to be evaluated as if they were valid.

Weakness: CWE-917 (Improper Neutralization of Special Elements used in an Expression Language Statement), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2021-28170?

6 open source packages ship an affected version, including com.sun.el:el-ri, org.glassfish:jakarta.el and org.glassfish:javax.el. It affects 4 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `com.sun.el:el-ri` | Maven | All versions | 3.0.4 |
| `com.sun.el:el-ri` | Maven | All versions | 3.0.4 |
| `org.glassfish:jakarta.el` | Maven | All versions | 3.0.4 |
| `org.glassfish:jakarta.el` | Maven | All versions | 3.0.4 |
| `org.glassfish:javax.el` | Maven | All versions to 3.0.1-b12 | None |
| `org.glassfish:javax.el` | Maven | All versions to 3.0.1-b12 | None |

Products: Eclipse Jakarta Expression Language, Oracle Communications Cloud Native Core Policy, Oracle Weblogic Server, Quarkus Quarkus.

## How do I fix CVE-2021-28170?

Upgrade com.sun.el:el-ri to 3.0.4 or later.

## Is CVE-2021-28170 being exploited?

There is no known exploitation of CVE-2021-28170 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-28170 and fix it if it is affected.

What it is: CVE-2021-28170 is a medium-severity code injection vulnerability in Oracle Communications Cloud Native Core Policy, published on 26 May 2021. 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-2021-28170 in the wild and no public exploit code.

Affected packages and fixed versions:
- com.sun.el:el-ri (Maven): affected all versions; fixed in 3.0.4
- com.sun.el:el-ri (Maven): affected all versions; fixed in 3.0.4
- org.glassfish:jakarta.el (Maven): affected all versions; fixed in 3.0.4
- org.glassfish:jakarta.el (Maven): affected all versions; fixed in 3.0.4
- org.glassfish:javax.el (Maven): affected all versions up to 3.0.1-b12; no fix listed
- org.glassfish:javax.el (Maven): affected all versions up to 3.0.1-b12; 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-2021-28170/ (Markdown: https://insights.sbomify.com/CVE-2021-28170/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-28170
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-28170
- OSV: https://osv.dev/vulnerability/CVE-2021-28170

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-28170/
Summaries are generated and may contain mistakes; the official description above is the record.