How severe is CVE-2021-22569?

CVE-2021-22569 has a CVSS score of 5.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-22569?

CVE-2021-22569 affects the following packages: com.google.protobuf:protobuf-java (Maven), com.google.protobuf:protobuf-java (Maven), com.google.protobuf:protobuf-java (Maven), com.google.protobuf:protobuf-kotlin (Maven), com.google.protobuf:protobuf-kotlin (Maven), google-protobuf (RubyGems). Ecosystems affected: Maven, RubyGems.

How do I fix CVE-2021-22569?

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.

How do I detect CVE-2021-22569 in my Maven, RubyGems dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.google.protobuf:protobuf-java. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2021-22569 if there is no patch (or I can't update yet)?

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 does O3 Security protect against CVE-2021-22569?

O3 pinpoints whether CVE-2021-22569 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2021-22569 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2021-22569, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-22569?

CVE-2021-22569 has an EPSS (Exploit Prediction Scoring System) score of 1.7%, placing it in the 74th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-22569?

CVE-2021-22569 is classified as CWE-696 (CWE-696). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-22569 published, and has it been updated?

CVE-2021-22569 was published on January 10, 2022 and was last updated on April 11, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2021-22569: A potential Denial of Service issue in protobuf…

EPSS Exploitation Probability

via FIRST.org ↗

1.7%probability of exploitation in next 30 days

Lower Risk74th percentile+1.18%

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.

Blast Radius

6 pkgs affected

☕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-protobuf

Real-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

An issue in protobuf-java allowed the interleaving of com.google.protobuf.UnknownFieldSet fields in such a way that would be processed out of order. A small malicious payload can occupy the parser for several minutes by creating large numbers of short-lived objects that cause frequent, repeated pauses. We recommend upgrading libraries beyond the vulnerable versions.

Affected Packages

6 total 6 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`com.google.protobuf:protobuf-java`	all versions	3.16.1
☕Maven	`com.google.protobuf:protobuf-java`	≥ 3.18.0&&< 3.18.2	3.18.2
☕Maven	`com.google.protobuf:protobuf-java`	≥ 3.19.0&&< 3.19.2	3.19.2
☕Maven	`com.google.protobuf:protobuf-kotlin`	≥ 3.18.0&&< 3.18.2	3.18.2
☕Maven	`com.google.protobuf:protobuf-kotlin`	≥ 3.19.0&&< 3.19.2	3.19.2
💎RubyGems	`google-protobuf`	all versions	3.19.2

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.google.protobuf:protobuf-java. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
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 pinpoints whether CVE-2021-22569 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

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.

Frequently Asked Questions

An issue in protobuf-java allowed the interleaving of com.google.protobuf.UnknownFieldSet fields in such a way that would be processed out of order. A small malicious payload can occupy the parser for several minutes by creating large numbers of short-lived objects that cause frequent, repeated pauses. We recommend upgrading libraries beyond the vulnerable versions.

O3 Security · Impact-Aware SCA

Is CVE-2021-22569 in your dependencies?

O3 detects CVE-2021-22569 across Maven, RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works

CVE-2021-22569