CVE-2021-22898: curl 7.7 through 7.76.1 suffers from an information disclosure when the `-t` command line option known as `CURLOPT_TELNETOPTIONS` in libcurl is used to send variable=content pairs to TELNET servers. Due to a flaw in the option parser for sending NEW_ENV variables libcurl could be made to pass on uninitialized data from a stack based buffer to the server resulting in potentially revealing sensitive internal information to the server using a clear-text network protocol.

Overview

Severity

Low (CVSS 3.1)

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N

Exploit Status

Not Exploited

Patch Tuesday

2021-Jun

Released

2021-06-23

Last Updated

2021-12-16

EPSS Score

0.13% (percentile: 31.9%)

FAQ

Is Azure Linux the only Microsoft product that includes this open-source library and is therefore potentially affected by this vulnerability? One of the main benefits to our customers who choose to use the Azure Linux distro is the commitment to keep it up to date with the most recent and most secure versions of the open source libraries with which the distro is composed. Microsoft is committed to transparency in this work which is why we began publishing CSAF/VEX in October 2025. See this blog post for more information. If impact to additional products is identified, we will update the CVE to reflect this.

Affected Products (2)

Other

• 19039-16820
• 19009-16823

Revision History

• 2021-06-23: Information published.
• 2021-12-16: Added curl to CBL-Mariner 2.0