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CVE-2021-22947

5.9 · MEDIUM

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…

Published Sep 29, 2021CWE-310EPSS 3.01%

Overview

CVE-2021-22947 is a medium-severity vulnerability. It was published on September 29, 2021 and has a CVSS 3.1 base score of 5.9 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.9, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refseclists.org/fulldisclosure/2022/Mar/29Refcert-portal.siemens.com/productcert/pdf/ssa-389290.pdfRefhackerone.com/reports/1334763Reflists.debian.org/debian-lts-announce/2021/09/msg00022.htmlReflists.debian.org/debian-lts-announce/2022/08/msg00017.htmlReflists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/APOAK4X73EJTAPTSVT7IRVDMUWVXNWGD/Reflists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RWLEC6YVEM2HWUBX67SDGPSY4CQB72OE/Refsecurity.gentoo.org/glsa/202212-01Refsecurity.netapp.com/advisory/ntap-20211029-0003/Refsupport.apple.com/kb/HT213183

How CyberStrike helps

Frequently asked questions

What is CVE-2021-22947?

CVE-2021-22947 is a medium-severity vulnerability. It was published on September 29, 2021 and has a CVSS 3.1 base score of 5.9 (MEDIUM).

How severe is CVE-2021-22947?

This vulnerability has a CVSS 3.1 base score of 5.9, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2021-22947?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-22947?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-22947 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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