CVE-2019-17638
Description
From CVE.org
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).
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.7 | 9.4 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | High | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | Low | Low | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
Red Hat CVSS v3 Score Explanation
Attack Complexity Low (AC:L) -> Attack Complexity High (AC:H):
We disagree with the original scoring of a low attack complexity, we believe the impact is significantly different depending on the specific applications handling, that is to say a successful attack depends on conditions beyond the attacker's control, we believe those conditions are -
*) The attack has a prerequisite of a response header injection, in other words the attacker would need to be able to alter the response header contents to achieve the double free.
*) In order to have a high impact upon confidentiality and integrity there is significant conditional factors to do with timing that must be present
The attacker and target client must have active connections at the same time
The same ByteBuffer space must be acquired by two different threads at the same time, this is a race condition and would require repeated and sustained attack
The Bytebuffer must be of the correct sizing to avoid corruption to achieve C:H I:H
Understanding the Weakness (CWE)
Availability,Integrity
Technical Impact: DoS: Crash, Exit, or Restart
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