CURL-CVE-2021-22898

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Source
https://curl.se/docs/CVE-2021-22898.html
Import Source
https://curl.se/docs/CURL-CVE-2021-22898.json
JSON Data
https://api.osv.dev/v1/vulns/CURL-CVE-2021-22898
Aliases
Published
2021-05-26T08:00:00Z
Modified
2024-01-25T02:42:49.602163Z
Summary
TELNET stack contents disclosure
Details

curl supports the -t command line option, known as CURLOPT_TELNETOPTIONS in libcurl. This rarely used option is used to send variable=content pairs to TELNET servers.

Due to 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. Therefore potentially revealing sensitive internal information to the server using a clear-text network protocol.

This could happen because curl did not check the return code from a sscanf(command, "%127[^,],%127s") function invoke correctly, and would leave the piece of the send buffer uninitialized for the value part if it was provided longer than 127 bytes. The buffer used for this is 2048 bytes big and the variable part of the variable=content pairs would be stored correctly in the send buffer, making curl sending "interleaved" bytes sequences of stack contents. A single curl TELNET handshake could then be made to send off a total of around 1800 bytes of (non-contiguous) stack contents in this style:

[control byte]name[control byte]
stack contents
[control byte]name[control byte]
stack contents
...

An easy proof of concept command line looks like this:

curl telnet://example.com -tNEW_ENV=a,bbbbbb (256 'b's)
Database specific 
{
    "CWE": {
        "id": "CWE-457",
        "desc": "Use of Uninitialized Variable"
    },
    "award": {
        "amount": "1000",
        "currency": "USD"
    },
    "URL": "https://curl.se/docs/CVE-2021-22898.json",
    "package": "curl",
    "severity": "Medium",
    "issue": "https://hackerone.com/reports/1176461",
    "www": "https://curl.se/docs/CVE-2021-22898.html",
    "last_affected": "7.76.1"
}
References
Credits
    • Harry Sintonen - FINDER
    • Harry Sintonen - REMEDIATION_DEVELOPER

Affected packages

Git / github.com/curl/curl.git

Affected ranges

Type
SEMVER
Events
Introduced
7.7
Fixed
7.77.0
Type
GIT
Repo
https://github.com/curl/curl.git
Events
Introduced
a1d6ad26100bc493c7b04f1301b1634b7f5aa8b4
Fixed
39ce47f219b09c380b81f89fe54ac586c8db6bde

Affected versions

7.*

7.10
7.10.1
7.10.2
7.10.3
7.10.4
7.10.5
7.10.6
7.10.7
7.10.8
7.11.0
7.11.1
7.11.2
7.12.0
7.12.1
7.12.2
7.12.3
7.13.0
7.13.1
7.13.2
7.14.0
7.14.1
7.15.0
7.15.1
7.15.2
7.15.3
7.15.4
7.15.5
7.16.0
7.16.1
7.16.2
7.16.3
7.16.4
7.17.0
7.17.1
7.18.0
7.18.1
7.18.2
7.19.0
7.19.1
7.19.2
7.19.3
7.19.4
7.19.5
7.19.6
7.19.7
7.20.0
7.20.1
7.21.0
7.21.1
7.21.2
7.21.3
7.21.4
7.21.5
7.21.6
7.21.7
7.22.0
7.23.0
7.23.1
7.24.0
7.25.0
7.26.0
7.27.0
7.28.0
7.28.1
7.29.0
7.30.0
7.31.0
7.32.0
7.33.0
7.34.0
7.35.0
7.36.0
7.37.0
7.37.1
7.38.0
7.39.0
7.40.0
7.41.0
7.42.0
7.42.1
7.43.0
7.44.0
7.45.0
7.46.0
7.47.0
7.47.1
7.48.0
7.49.0
7.49.1
7.50.0
7.50.1
7.50.2
7.50.3
7.51.0
7.52.0
7.52.1
7.53.0
7.53.1
7.54.0
7.54.1
7.55.0
7.55.1
7.56.0
7.56.1
7.57.0
7.58.0
7.59.0
7.60.0
7.61.0
7.61.1
7.62.0
7.63.0
7.64.0
7.64.1
7.65.0
7.65.1
7.65.2
7.65.3
7.66.0
7.67.0
7.68.0
7.69.0
7.69.1
7.7
7.7.1
7.7.2
7.7.3
7.70.0
7.71.0
7.71.1
7.72.0
7.73.0
7.74.0
7.75.0
7.76.0
7.76.1
7.8
7.8.1
7.9
7.9.1
7.9.2
7.9.3
7.9.4
7.9.5
7.9.6
7.9.7
7.9.8