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Date: Wed, 11 May 2022 08:40:29 +0200 (CEST)
From: Daniel Stenberg <>
To: curl security announcements -- curl users <>,, libcurl hacking <>,
Subject: [SECURITY ADVISORY] curl: CERTINFO never-ending busy-loop

CERTINFO never-ending busy-loop

Project curl Security Advisory, May 11 2022 -


libcurl provides the `CURLOPT_CERTINFO` option to allow applications to
request details to be returned about a TLS server's certificate chain.

Due to an erroneous function, a malicious server could make libcurl built with
NSS get stuck in a never-ending busy-loop when trying to retrieve that

We are not aware of any exploit of this flaw.


This flaw was introduced in [commit
f6c335d63f](, shipped in curl
7.34.0 when libcurl added support for CERTINFO using NSS.

This feature is not accessible from the command line tool.

The Common Vulnerabilities and Exposures (CVE) project has assigned the name
CVE-2022-27781 to this issue.

CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')

Severity: Low


- Affected versions: curl 7.34.0 to and including 7.83.0
- Not affected versions: curl < 7.34.0 and curl >= 7.83.1

libcurl is used by many applications, but not always advertised as such!


A [fix for CVE-2022-27781](


  A - Upgrade curl to version 7.83.1

  B - Apply the patch to your local version

  C - Do not use the `CURLOPT_CERTINFO` option


This issue was reported to the curl project on April 30, 2022. We contacted
distros@...nwall on May 5.

libcurl 7.83.1 was released on May 11 2022, coordinated with the publication
of this advisory.


This issue was reported by Florian Kohnhäuser. Patched by Daniel Stenberg.

Thanks a lot!


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