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MEDIUM

CVE-2021-22925

CVSS v3

5.3

MEDIUM

EPSS Score

5.4 %

exploit probability, as of 2026-10-19

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • libcurlAlmaLinux:8all versions · fixed in 7.61.1-22.el8and 3 other packages

Vendor advisories

  • CVE-2021-22925 Red Hat Product Security45 products fixed · 22 known affected

    curl: Incorrect fix for CVE-2021-22898 TELNET stack contents disclosure

    rh-dotnet21-curl.src as a component of .NET Core 2.1 on Red Hat Enterprise Linux · rh-dotnet21-libcurl as a component of .NET Core 2.1 on Red Hat Enterprise Linux · rh-dotnet21-libcurl-devel as a component of .NET Core 2.1 on Red Hat Enterprise Linux

  • ICSA-23-348-10 CISA5 known affected

    Siemens SIMATIC S7-1500

    SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) · SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)

  • SSA-398330 Siemens ProductCERT5 known affected

    SSA-398330: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP >= V3.1.0 and < V3.1.5

    SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= V3.1.0 < V3.1.5 · SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= V3.1.0 < V3.1.5 · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= V3.1.0 < V3.1.5

  • ICSA-22-167-17 CISA1 known affected

    Siemens OpenSSL Affecting Industrial Products

    SINEMA Remote Connect Server

  • SSA-484086 Siemens ProductCERT1 known affected

    SSA-484086: Multiple Vulnerabilities in SINEMA Remote Connect Server before V3.1

    SINEMA Remote Connect Server

  • ICSA-22-069-09 CISA1 known affected

    Siemens SINEC INS

    SINEC INS

2 more advisories

Full record on NVD

Description

curl supports the `-t` command line option, known as `CURLOPT_TELNETOPTIONS`in libcurl. This rarely used option is used to send variable=content pairs toTELNET servers.Due to flaw in the option parser for sending `NEW_ENV` variables, libcurlcould be made to pass on uninitialized data from a stack based buffer to theserver. Therefore potentially revealing sensitive internal information to theserver using a clear-text network protocol.This could happen because curl did not call and use sscanf() correctly whenparsing the string provided by the application.

Technical details

Published
2021-08-05

Frequently asked questions

What is CVE-2021-22925?

curl supports the `-t` command line option, known as `CURLOPT_TELNETOPTIONS`in libcurl. This rarely used option is used to send variable=content pairs toTELNET servers.Due to flaw in the option parser for sending `NEW_ENV` variables, libcurlcould be made to pass on uninitialized data from a stack based buffer to theserver. Therefore potentially revealing sensitive internal information to theserver using a clear-text network protocol.This could happen because curl did not call and use sscanf() correctly whenparsing the string provided by the application.

Is CVE-2021-22925 actively exploited?

Active exploitation of CVE-2021-22925 has not been confirmed. Its EPSS score was 5.4% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-22925?

CVE-2021-22925 has a CVSS v3 base score of 5.3 (MEDIUM severity).

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