PT-2021-3530 · Curl+9 · Curl+9
Published
2021-04-27
·
Updated
2026-05-18
·
CVE-2021-22898
CVSS v3.1
3.1
Low
| Vector | AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N |
Name of the Vulnerable Software and Affected Versions
curl versions 7.7 through 7.76.1
Description
The issue is related to the
-t command line option, known as CURLOPT TELNETOPTIONS in libcurl, which 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, potentially revealing sensitive internal information to the server using a clear-text network protocol. This happens because curl does not check the return code from a sscanf function invoke correctly, leaving the piece of the send buffer uninitialized for the value part if it was provided longer than 127 bytes.Recommendations
For curl versions 7.7 through 7.76.1, as a temporary workaround, consider disabling the use of the
-t command line option, known as CURLOPT TELNETOPTIONS, until a patch is available. Restrict access to TELNET servers to minimize the risk of exploitation. Avoid using the NEW ENV variable in the affected API endpoint until the issue is resolved. At the moment, there is no information about a newer version that contains a fix for this vulnerability.Exploit
Information Disclosure
Use of Uninitialized Resource
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Related Identifiers
Affected Products
Alt Linux
Almalinux
Astra Linux
Centos
Linuxmint
Red Hat
Rocky Linux
Suse
Ubuntu
Curl