CVE-2021-28170 is a medium-severity (CVSS 5.3) Improper Input Validation vulnerability in com.sun.el:el-ri. 2 public exploit references exist, so weaponization risk is real. A fix is available for com.sun.el:el-ri — see the affected versions and patch details below.
Improper Input Validation in Jakarta Expression Language
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-28170 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,386 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
com.sun.el:el-ri☕org.glassfish:jakarta.el☕org.glassfish:javax.elReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | com.sun.el:el-ri | all versions | 3.0.4com.sun.el:el-ri:3.0.4 |
| ☕Maven | org.glassfish:jakarta.el | all versions | 3.0.4org.glassfish:jakarta.el:3.0.4 |
| ☕Maven | org.glassfish:javax.el | all versions | No fix |
Affected Products
jakarta expression languageeclipsecommunications cloud native core policyoracleweblogic serveroraclequarkusquarkusResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.sun.el:el-ri, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update com.sun.el:el-ri to 3.0.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-28170 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| EAP 7.3.9 release | jakarta.el | RHSA-2021:3471 |
| Red Hat build of Quarkus 2.2.5 | jakarta.el | RHSA-2022:0589 |
| Red Hat EAP-XP 2.0.0 via EAP 7.3.x base | jakarta.el | RHSA-2021:3516 |
| Red Hat Fuse 7.10 | jakarta.el | RHSA-2021:5134 |
| Red Hat JBoss Enterprise Application Platform | org.glassfish/jakarta.el:3.0.3.redhat-00006 | RHSA-2021:3660 |
| Red Hat JBoss Enterprise Application Platform 7.1 EUS for RHEL 7 | eap7-glassfish-el-0:3.0.1-4.b08_redhat_00005.1.ep7.el7 | RHSA-2025:9582 |
| Red Hat JBoss Enterprise Application Platform 7.3 for RHEL 6 | eap7-apache-commons-io-0:2.10.0-1.redhat_00001.1.el6eap | RHSA-2021:3466 |
| Red Hat JBoss Enterprise Application Platform 7.3 for RHEL 7 | eap7-apache-commons-io-0:2.10.0-1.redhat_00001.1.el7eap | RHSA-2021:3467 |
Frequently Asked Questions
Is CVE-2021-28170 in your dependencies?
Find it across Maven, including transitive dependencies.