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Fencer Vulns
medium 5.3

CVE-2021-22925 json

curl supports the `-t` command line option, known as `CURLOPT_TELNETOPTIONS`in libcurl.

published 2021-08-05 5 y ago modified 2026-10-14 26 d ago also EUVD-2021-10054 , JLSEC-2026-1337

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
5.4%
EPSS 5.4% chance of exploitation in 30 days, percentile 92%
public exploits
0
none known

Summary

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.

Patch / fix

  • julia LibCURL_jll 7.81.0+0
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP V3.1.5
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • curl Ubuntu 18.04 LTS 7.58.0-2ubuntu3.14
  • curl Ubuntu 20.04 LTS 7.68.0-1ubuntu2.6
  • curl Ubuntu Pro 14.04 LTS 7.35.0-1ubuntu2.20+esm14
  • curl Ubuntu Pro 16.04 LTS 7.47.0-1ubuntu2.19+esm3

ubuntu advisories UBUNTU-CVE-2021-22925

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • curl RHEL 8 7.61.1-22.el8
  • libcurl RHEL 8 7.61.1-22.el8
  • libcurl-minimal RHEL 8 7.61.1-22.el8

red hat advisories RHSA-2021:4511

  • curl SLES for SAP 12 SP5, SLES 12 SP5, SLE Software Development Kit 12 SP5 7.60.0-11.23.1
  • curl SLES for SAP 15 SP1, SLES for SAP 15, SLES 15-LTSS +10 more 7.60.0-3.47.1
  • curl SLE Module for Basesystem 15 SP3, SLE Module for Basesystem 15 SP2, SLE Micro 5.0 7.66.0-4.22.1
  • curl-openssl1 SLES 11-SECURITY 7.37.0-70.71.1
  • curl SLES for SAP 12 SP4, SLES 12 SP4-LTSS, OpenStack Cloud Crowbar 9 +1 more 7.60.0-4.25.1

suse advisories SUSE-SU-2021:2462-1SUSE-SU-2021:2440-1SUSE-SU-2021:2439-1SUSE-SU-2021:14768-1SUSE-SU-2021:2425-1

  • curl openSUSE Leap 15.2 7.66.0-lp152.3.21.1
  • curl-mini openSUSE Leap 15.2 7.66.0-lp152.3.21.1
  • curl openSUSE Leap 15.3 7.66.0-4.22.1

opensuse advisories openSUSE-SU-2021:1088-1openSUSE-SU-2021:2439-1

  • curl AlmaLinux 8 7.61.1-22.el8
  • libcurl AlmaLinux 8 7.61.1-22.el8
  • libcurl-minimal AlmaLinux 8 7.61.1-22.el8

almalinux advisories ALSA-2021:4511

  • curl Rocky Linux 8 7.61.1-22.el8

rocky linux advisories RLSA-2021:4511

  • curl Alpine 3.11 7.67.0-r5
  • curl Alpine 3.24, Alpine 3.23, Alpine 3.22 +10 more 7.78.0-r0

alpine advisories ALPINE-CVE-2021-22925

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • curl CBL-Mariner 2.0 7.76.0-5

azure linux advisories AZL-6363

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

  • curl Arch Linux 7.78.0-1
  • lib32-curl Arch Linux 7.78.0-1
  • libcurl-compat Arch Linux 7.78.0-1
  • lib32-libcurl-compat Arch Linux 7.78.0-1
  • libcurl-gnutls Arch Linux 7.78.0-1
  • lib32-libcurl-gnutls Arch Linux 7.78.0-1

arch linux advisories AVG-2194AVG-2195AVG-2196AVG-2197AVG-2198AVG-2199

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-22925 updated cvss 3.1

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

  • Red Hat .NET Core 2.1 on Red Hat Enterprise Linux rh-dotnet21-curl, rh-dotnet21-libcurl Red Hat .NET Core 3.1 on Red Hat Enterprise Linux rh-dotnet31-curl, rh-dotnet31-libcurl
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Ceph Storage 2 curl, libcurl Red Hat Enterprise Linux 6 curl, libcurl Red Hat Enterprise Linux 7 curl, libcurl
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat JBoss Core Services jbcs-httpd24-curl jbcs-httpd24-curl
    affected: workaround, no fix available
  • Red Hat Software Collections httpd24-curl, httpd24-libcurl
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Enterprise Linux BaseOS (v. 8) curl 7.61.1-22.el8, libcurl 7.61.1-22.el8, libcurl-minimal 7.61.1-22.el8
    fixed: vendor fix RHSA-2021:4511
  • Red Hat Enterprise Linux 9 curl, libcurl, curl-minimal, libcurl-minimal
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

cisa ICSA-23-348-10 updated cvss 5.3

Siemens SIMATIC S7-1500

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.0, < 3.1.5
    affected: fixed in V3.1.5, mitigation support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

cisa ICSA-22-167-17 updated cvss 5.3

Siemens OpenSSL Affecting Industrial Products

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
6 mo ago

Exploit prediction

5.37% chance of exploitation in the next 30 days, higher than 92% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • hackerone.com https://hackerone.com/reports/1223882 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:P/I:N/A:N
OSV 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Affected packages

ecosystem package affected fixed in
julia LibCURL_jll
<7.81.0+0
7.81.0+0

Affected products

  • n/a https://github.com/curl/curl
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

Classification

Weakness
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
  • CWE-908 Use of Uninitialized Resource
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.