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Authentication Bypass by Capture-replay Affecting org.jenkins-ci.main:jenkins-core package, versions [,2.452)

0.0
medium

Snyk CVSS

    Attack Complexity High
    Integrity High

    Threat Intelligence

    Exploit Maturity Proof of concept
    EPSS 96.23% (100th percentile)
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NVD
5.9 medium
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Red Hat
5.9 medium
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SUSE
5.9 medium

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  • Snyk ID SNYK-JAVA-ORGJENKINSCIMAIN-6619757
  • published 18 Apr 2024
  • disclosed 18 Dec 2023
  • credit Fabian Bäumer, Marcus Brinkmann, Jörg Schwenk
Report a new vulnerability Found a mistake?

Introduced: 18 Dec 2023

CVE-2023-48795 Open this link in a new tab
CWE-294 Open this link in a new tab

How to fix?

Upgrade org.jenkins-ci.main:jenkins-core to version 2.452 or higher.

Overview

org.jenkins-ci.main:jenkins-core is an open source automation server.

Affected versions of this package are vulnerable to Authentication Bypass by Capture-replay during the establishment of the secure channel. An attacker can manipulate handshake sequence numbers to delete messages sent immediately after the channel is established.

Note:

  1. Sequence numbers are only validated once the channel is established and arbitrary messages are allowed during the handshake, allowing them to manipulate the sequence numbers.

  2. The potential consequences of the general Terrapin attack are dependent on the messages exchanged after the handshake concludes. If you are using a custom SSH service and do not resort to the authentication protocol, you should check that dropping the first few messages of a connection does not yield security risks.

Impact:

While cryptographically novel, there is no discernable impact on the integrity of SSH traffic beyond giving the attacker the ability to delete the message that enables some features related to keystroke timing obfuscation. To successfully carry out the exploitation, the connection needs to be protected using either the ChaCha20-Poly1305 or CBC with Encrypt-then-MAC encryption methods. The attacker must also be able to intercept and modify the connection's traffic.

Workaround

Temporarily disable the affected chacha20-poly1305@openssh.com encryption and *-etm@openssh.com MAC algorithms in the affected configuration, and use unaffected algorithms like AES-GCM instead.

Note

This only affects the Jenkins CLI client when using the -ssh connection mode, which is not the default.