Cleartext Transmission of Sensitive Information Affecting libcurl-minimal package, versions <0:7.61.1-18.el8_4.2



    Attack Complexity High
    User Interaction Required
    Scope Changed
    Confidentiality High
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5.9 medium
Expand this section
5.9 medium
Expand this section
Red Hat
6.1 medium

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  • published 15 Sep 2021
  • disclosed 15 Sep 2021

How to fix?

Upgrade Centos:8 libcurl-minimal to version 0:7.61.1-18.el8_4.2 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libcurl-minimal package and not the libcurl-minimal package as distributed by Centos:8. See How to fix? for Centos:8 relevant fixed versions and status.

When curl >= 7.20.0 and <= 7.78.0 connects to an IMAP or POP3 server to retrieve data using STARTTLS to upgrade to TLS security, the server can respond and send back multiple responses at once that curl caches. curl would then upgrade to TLS but not flush the in-queue of cached responses but instead continue using and trustingthe responses it got before the TLS handshake as if they were authenticated.Using this flaw, it allows a Man-In-The-Middle attacker to first inject the fake responses, then pass-through the TLS traffic from the legitimate server and trick curl into sending data back to the user thinking the attacker's injected data comes from the TLS-protected server.