CVE-2021-22569 — protobuf-java
MEDIUMCVE-2021-22569 is a medium-severity (CVSS 5.5) CWE-696 vulnerability in com.google.protobuf:protobuf-java. 1 public exploit reference exists, so weaponization risk is real. A fix is available for com.google.protobuf:protobuf-java — see the affected versions and patch details below.
A potential Denial of Service issue in protobuf-java
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2021-22569.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2021-22569 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
com.google.protobuf:protobuf-java☕com.google.protobuf:protobuf-java☕com.google.protobuf:protobuf-java☕com.google.protobuf:protobuf-kotlin☕com.google.protobuf:protobuf-kotlin💎google-protobufReal-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
Summary
A potential Denial of Service issue in protobuf-java was discovered in the parsing procedure for binary data.
Reporter: OSS-Fuzz
Affected versions: All versions of Java Protobufs (including Kotlin and JRuby) prior to the versions listed below. Protobuf "javalite" users (typically Android) are not affected.
Severity
CVE-2021-22569 High - CVSS Score: 7.5, An implementation weakness in how unknown fields are parsed in Java. A small (~800 KB) malicious payload can occupy the parser for several minutes by creating large numbers of short-lived objects that cause frequent, repeated GC pauses.
Proof of Concept
For reproduction details, please refer to the oss-fuzz issue that identifies the specific inputs that exercise this parsing weakness.
Remediation and Mitigation
Please update to the latest available versions of the following packages:
- protobuf-java (3.16.1, 3.18.2, 3.19.2)
- protobuf-kotlin (3.18.2, 3.19.2)
- google-protobuf [JRuby gem only] (3.19.2)
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | com.google.protobuf:protobuf-java | all versions | 3.16.1com.google.protobuf:protobuf-java:3.16.1 |
| ☕Maven | com.google.protobuf:protobuf-java | ≥ 3.18.0&&< 3.18.2 | 3.18.2com.google.protobuf:protobuf-java:3.18.2 |
| ☕Maven | com.google.protobuf:protobuf-java | ≥ 3.19.0&&< 3.19.2 | 3.19.2com.google.protobuf:protobuf-java:3.19.2 |
| ☕Maven | com.google.protobuf:protobuf-kotlin | ≥ 3.18.0&&< 3.18.2 | 3.18.2com.google.protobuf:protobuf-kotlin:3.18.2 |
| ☕Maven | com.google.protobuf:protobuf-kotlin | ≥ 3.19.0&&< 3.19.2 | 3.19.2com.google.protobuf:protobuf-kotlin:3.19.2 |
| 💎RubyGems | google-protobuf | all versions | 3.19.2bundle update google-protobuf --conservative |
Research 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.google.protobuf:protobuf-java, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update com.google.protobuf:protobuf-java to 3.16.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-22569 is resolved across your whole dependency graph.
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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2021-22569 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2021-22569. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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 |
|---|---|---|
| Red Hat build of Quarkus 2.7.5 | protobuf-java | RHSA-2022:4623 |
| Red Hat Fuse 7.11 | protobuf-java | RHSA-2022:5532 |
| RHINT Camel-Q 2.2.1 | see advisory | RHSA-2022:1013 |
| RHINT Debezium 1.9.7 | protobuf-java | RHSA-2022:7896 |
| RHINT Service Registry 2.3.0 GA | protobuf-java | RHSA-2022:6835 |
| RHPAM 7.13.0 async | protobuf-java | RHSA-2022:5903 |
| Text-Only RHOAR | protobuf-java | RHSA-2022:8761 |
Frequently Asked Questions
Is CVE-2021-22569 in your dependencies?
O3 Security finds CVE-2021-22569 across Maven, RubyGems dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.