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Fencer Vulns
low 3.1

CVE-2021-22898 json

curl 7.7 through 7.76.1 suffers from an information disclosure when the `-t` command line option, known as `CURLOPT_TELNETOPTIONS` in libcu…

published 2021-06-11 5 y ago modified 2026-10-14 26 d ago also EUVD-2021-10030 , JLSEC-2026-1334

cvss
3.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
4.5%
EPSS 4.5% chance of exploitation in 30 days, percentile 91%
public exploits
0
none known

Summary

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.

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 Debian 14, Debian 13, Debian 12 7.79.1-1

debian advisories DEBIAN-CVE-2021-22898

  • 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-2021-22898

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 11 SP4-LTSS, SLE Point of Sale 11 SP3 7.37.0-70.66.1
  • curl-openssl1 SLES 11-SECURITY 7.37.0-70.66.1
  • curl SLES for SAP 15 SP1, SLES for SAP 15, SLES 15-LTSS +10 more 7.60.0-3.42.1
  • curl SLES for SAP 12 SP4, SLES 12 SP4-LTSS, OpenStack Cloud Crowbar 9 +1 more 7.60.0-4.20.1
  • curl-openssl1 SLES 11-SECURITY 7.37.0-70.63.1
  • curl SLES for SAP 12 SP5, SLES 12 SP5, SLE Software Development Kit 12 SP5 7.60.0-11.18.1
  • curl SLE Module for Basesystem 15 SP3, SLE Module for Basesystem 15 SP2, SLE Micro 5.0 7.66.0-4.17.1

suse advisories SUSE-SU-2021:14760-1SUSE-SU-2021:1809-1SUSE-SU-2021:1786-1SUSE-SU-2021:14735-1SUSE-SU-2021:1763-1SUSE-SU-2021:1762-1

  • curl openSUSE Tumbleweed 7.79.1-1.1
  • curl openSUSE Leap 15.3 7.66.0-4.17.1
  • curl-mini openSUSE Leap 15.3 7.66.0-4.17.1
  • curl openSUSE Leap 15.2 7.66.0-lp152.3.18.1
  • curl-mini openSUSE Leap 15.2 7.66.0-lp152.3.18.1

opensuse advisories openSUSE-SU-2024:10582-1openSUSE-SU-2021:1762-1openSUSE-SU-2021:0808-1

  • 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 3.10 7.66.0-r4
  • curl Alpine 3.11 7.67.0-r4
  • curl Alpine 3.24, Alpine 3.23, Alpine 3.22 +10 more 7.77.0-r0

alpine advisories ALPINE-CVE-2021-22898

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-6359

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 7.77.0-1
  • lib32-curl Arch Linux 7.77.0-1
  • libcurl-compat Arch Linux 7.77.0-1
  • lib32-libcurl-compat Arch Linux 7.77.0-1
  • libcurl-gnutls Arch Linux 7.77.0-1
  • lib32-libcurl-gnutls Arch Linux 7.77.0-1

arch linux advisories AVG-1995AVG-1996AVG-1997AVG-1998AVG-1999AVG-2000

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-2021-22898 updated cvss 3.1

curl: 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 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 3.1

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 SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

4.51% chance of exploitation in the next 30 days, higher than 91% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • hackerone.com https://hackerone.com/reports/1176461 referenced PoC, tagged "exploit" by a source, unverified
  • curl.se https://curl.se/docs/CVE-2021-22898.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N
NVD 3.1 3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N
CNA 3.1 3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N
NVD 2.0 2.6 AV:N/AC:H/Au:N/C:P/I:N/A:N
OSV 3.1 3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/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-909 Missing Initialization of 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.

CPEs and fixed versions use Anchore's correction of NVD's data: Improve version ranges to indicate fix.