Jenkins—a well-liked open-supply automation server software—published an advisory on Monday regarding a critical vulnerability in the Jetty web server that could end result in memory corruption and bring about confidential information and facts to be disclosed.
Tracked as CVE-2019-17638, the flaw has a CVSS rating of 9.4 and impacts Eclipse Jetty versions 9.4.27.v20200227 to 9.4.29.v20200521—a comprehensive-showcased instrument that offers a Java HTTP server and web container for use in program frameworks.
“Jenkins bundles Winstone-Jetty, a wrapper close to Jetty, to act as HTTP and servlet server when started off employing java -jar jenkins.war. This is how Jenkins is operate when making use of any of the installers or deals, but not when operate applying servlet containers these kinds of as Tomcat,” browse the advisory.
“The vulnerability may permit unauthenticated attackers to receive HTTP reaction headers that may possibly include sensitive knowledge meant for one more person.”
The flaw, which impacts Jetty and Jenkins Core, appears to have been introduced in Jetty edition 9.4.27, which extra a system to take care of large HTTP response headers and prevent buffer overflows.
“The issue was in the scenario of a buffer overflow, we introduced the header buffer, but did not null the field,” Jetty’s task head Greg Wilkins explained.
To manage this, Jetty throws an exception to produce an HTTP 431 mistake, which causes the HTTP reaction headers to be launched to the buffer pool twice, in transform producing memory corruption and details disclosure.
Hence, due to the double launch, two threads can purchase the same buffer from the pool at the similar time and most likely letting one particular ask for to accessibility a response created by the other thread, which may well include session identifiers, authentication qualifications, and other delicate info.
Place differently, “while thread1 is about to use the ByteBuffer to generate reaction1 data, thread2 fills the ByteBuffer with reaction2 knowledge. Thread1 then proceeds to write the buffer that now incorporates reaction2 data. This final results in client1, which issued ask for1 and expects responses, to see reaction2 which could incorporate sensitive details belonging to customer2.”
In a person case, the memory corruption created it possible for clientele to go among periods, therefore owning cross-account obtain, as authentication cookies from 1 user’s reaction were being sent to a different person, thereby letting consumer A to soar in person B’s session.
After the security implications ended up disclosed, the vulnerability was dealt with in Jetty 9.4.30.v20200611 launched previous thirty day period. Jenkins, which bundles Jetty by way of a command-line interface known as Winstone, has patched the flaw in its utility in Jenkins 2.243 and Jenkins LTS 2.235.5 released yesterday.
It is proposed that Jenkins consumers update their program to the hottest model to mitigate the buffer corruption flaw.
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