CVE-2019-17638

What it is

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).

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure, data tampering.

Exploit odds

11.1% chance of exploitation in the next 30 days (EPSS). Higher than most.

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2020-07-09 18:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 02:24 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 11.1% in the next 30 days (EPSS).
• Severity: 9.4 CRITICAL (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2020-07-09 18:15 UTC

Last modified

2026-06-17 02:24 UTC

Exploit probability

11.1% · EPSS, next 30 days

Weakness

CWE-672

Record status

Modified

Affected

• Eclipse Jetty 9.4.27
• Eclipse Jetty 9.4.28
• Eclipse Jetty 9.4.29

Attack profile CVSS 3.1 · 9.4

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

Low

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2019-17638.md and follow it. Check whether this project is affected by CVE-2019-17638. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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