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Fencer Vulns
critical 9.8

CVE-2023-27533 json

A vulnerability in input validation exists in curl <8.0 during communication using the TELNET protocol may allow an attacker to pass on mal…

published 2023-03-30 3 y ago modified 2026-10-14 25 d ago also EUVD-2023-31288 , JLSEC-2026-405

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.2%
EPSS 2.2% chance of exploitation in 30 days, percentile 82%
public exploits
0
none known

Summary

A vulnerability in input validation exists in curl <8.0 during communication using the TELNET protocol may allow an attacker to pass on maliciously crafted user name and "telnet options" during server negotiation. The lack of proper input scrubbing allows an attacker to send content or perform option negotiation without the application's intent. This vulnerability could be exploited if an application allows user input, thereby enabling attackers to execute arbitrary code on the system.

Patch / fix

  • julia CURL_jll 8.5.0+0
  • julia LibCURL_jll 8.0.1+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 7.88.1-7

debian advisories DEBIAN-CVE-2023-27533

  • curl Ubuntu 18.04 LTS 7.58.0-2ubuntu3.24
  • curl Ubuntu 20.04 LTS 7.68.0-1ubuntu2.18
  • curl Ubuntu 22.04 LTS 7.81.0-1ubuntu1.10
  • curl Ubuntu Pro 14.04 LTS 7.35.0-1ubuntu2.20+esm15
  • curl Ubuntu Pro 16.04 LTS 7.47.0-1ubuntu2.19+esm8

ubuntu advisories UBUNTU-CVE-2023-27533

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 9 7.76.1-26.el9
  • libcurl RHEL 9 7.76.1-26.el9
  • curl-minimal RHEL 9 7.76.1-26.el9
  • libcurl-minimal RHEL 9 7.76.1-26.el9
  • jbcs-httpd24-curl jboss core services 1 8.0.1-1.el7jbcs
  • jbcs-httpd24-curl jboss core services 1 8.0.1-1.el8jbcs
  • jbcs-httpd24-httpd jboss core services 1 2.4.51-39.el7jbcs
  • jbcs-httpd24-httpd jboss core services 1 2.4.51-39.el8jbcs

red hat advisories RHSA-2023:6679RHSA-2023:3354

  • curl SLES for SAP 12 SP4, SLES 12 SP4-LTSS, SLES 12 SP4-ESPOS +2 more 7.60.0-4.56.1
  • curl SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLE High Performance Computing 15 SP1-LTSS +1 more 7.60.0-150000.51.1
  • curl SLE Real Time 15 SP3, SLE Micro 5.2, SLE Micro 5.1 7.66.0-150200.4.52.1
  • curl SLE Module for Basesystem 15 SP4, SLE Micro 5.3, openSUSE Leap Micro 5.3 +1 more 7.79.1-150400.5.18.1
  • curl SLES for SAP 12 SP5, SLES 12 SP5, SLE Software Development Kit 12 SP5 7.60.0-11.60.1

suse advisories SUSE-SU-2023:2228-1SUSE-SU-2023:2226-1SUSE-SU-2023:1711-1SUSE-SU-2023:1582-1SUSE-SU-2023:0865-1

  • curl openSUSE Tumbleweed 8.0.1-1.1

opensuse advisories openSUSE-SU-2024:12812-1

  • curl AlmaLinux 9 7.76.1-26.el9
  • libcurl AlmaLinux 9 7.76.1-26.el9
  • curl-minimal AlmaLinux 9 7.76.1-26.el9
  • libcurl-minimal AlmaLinux 9 7.76.1-26.el9

almalinux advisories ALSA-2023:6679

  • curl Alpine 3.16, Alpine 3.15, Alpine 3.14 8.0.1-r0
  • curl Alpine 3.17 7.88.1-r1
  • curl Alpine 3.24, Alpine 3.23, Alpine 3.22 +4 more 8.0.0-r0

alpine advisories ALPINE-CVE-2023-27533

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

  • cmake CBL-Mariner 2.0 3.21.4-12
  • mysql CBL-Mariner 2.0 8.0.34-1
  • rust CBL-Mariner 2.0 1.72.0-2
  • curl CBL-Mariner 2.0 8.0.1-1
  • cmake Azure Linux 3.0 3.28.2-1
  • tensorflow Azure Linux 3.0 2.16.1-1

azure linux advisories AZL-25783AZL-25804AZL-25812AZL-25894AZL-34608AZL-37878

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

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-2023-27533 updated cvss 4.3

curl: TELNET option IAC injection

  • Red Hat JBCS httpd 2.4.51.sp2
    fixed: vendor fix RHSA-2023:3355
  • Red Hat Enterprise Linux AppStream (v. 9) libcurl-devel 7.76.1-26.el9, curl-debuginfo 7.76.1-26.el9, curl-debugsource 7.76.1-26.el9, libcurl-debuginfo 7.76.1-26.el9, curl-minimal-debuginfo 7.76.1-26.el9, libcurl-minimal-debuginfo 7.76.1-26.el9 Red Hat Enterprise Linux BaseOS (v. 9) curl 7.76.1-26.el9, libcurl 7.76.1-26.el9, curl-minimal 7.76.1-26.el9, libcurl-minimal 7.76.1-26.el9
    fixed: vendor fix RHSA-2023:6679
  • Red Hat JBoss Core Services on RHEL 7 Server jbcs-httpd24-curl 8.0.1-1.el7jbcs, jbcs-httpd24-libcurl 8.0.1-1.el7jbcs Red Hat JBoss Core Services on RHEL 8 jbcs-httpd24-curl 8.0.1-1.el8jbcs, jbcs-httpd24-libcurl 8.0.1-1.el8jbcs
    fixed: vendor fix RHSA-2023:3354
  • Red Hat .NET Core 3.1 on Red Hat Enterprise Linux rh-dotnet31-curl, rh-dotnet31-libcurl Red Hat Enterprise Linux 6 curl, libcurl Red Hat Enterprise Linux 7 curl, libcurl Red Hat Enterprise Linux 8 curl, libcurl, libcurl-minimal Red Hat JBoss Core Services on RHEL 7 Server jbcs-httpd24-httpd 2.4.51-39.el7jbcs, jbcs-httpd24-mod_md 2.4.0-20.el7jbcs, jbcs-httpd24-mod_ssl 2.4.51-39.el7jbcs, jbcs-httpd24-openssl 1.1.1k-14.el7jbcs, jbcs-httpd24-apr-util 1.6.1-101.el7jbcs, jbcs-httpd24-mod_ldap 2.4.51-39.el7jbcs, +21 more Red Hat JBoss Core Services on RHEL 8 jbcs-httpd24-httpd 2.4.51-39.el8jbcs, jbcs-httpd24-mod_md 2.4.0-20.el8jbcs, jbcs-httpd24-mod_ssl 2.4.51-39.el8jbcs, jbcs-httpd24-openssl 1.1.1k-14.el8jbcs, jbcs-httpd24-apr-util 1.6.1-101.el8jbcs, jbcs-httpd24-mod_ldap 2.4.51-39.el8jbcs, +21 more
    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 8.8

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
yes
Technical impact
total
Assessed
8 mo ago

Exploit prediction

2.16% chance of exploitation in the next 30 days, higher than 82% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • hackerone.com https://hackerone.com/reports/1891474 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
OSV 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
julia CURL_jll
<8.5.0+0
8.5.0+0
julia LibCURL_jll
<8.0.1+0
8.0.1+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-75 Failure to Sanitize Special Elements into a Different Plane
  • CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component

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 fixes.