CVE-2023-27533

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DescriptionStatementAdditional informationAffected PackagesCVSS Score DetailsWeakness (CWE)AcknowledgementsFAQ

Description

The CVE Program describes this issue as:

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.

Statement

While this vulnerability exists in Curl, the potential impact is to a different component. The overall impact is limited to the telnet component. On its own this flaw has a limited to negligible effect on integrity of the entire system, therefore it has been rated as having a Low security impact. This is in alignment with upstream’s impact assessment, their advisory is linked in external references.

While this vulnerability exists in Curl, the potential impact is to a different component. The overall impact is limited to the telnet component. On its own this flaw has a limited to negligible effect on integrity of the entire system, therefore it has been rated as having a Low security impact. This is in alignment with upstream’s impact assessment, their advisory is linked in external references.

Additional information

  • Bugzilla 2179062: curl: TELNET option IAC injection
  • CWE-75: Failure to Sanitize Special Elements into a Different Plane (Special Element Injection)
  • FAQ: Frequently asked questions about CVE-2023-27533

Common Vulnerability Scoring System (CVSS) Score Details

Important note

CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).

CVSS v3 Score Breakdown
Red HatNVD

CVSS v3 Base Score

4.3

8.8

Attack Vector

Network

Network

Attack Complexity

Low

Low

Privileges Required

None

None

User Interaction

Required

Required

Scope

Unchanged

Unchanged

Confidentiality Impact

None

High

Integrity Impact

Low

High

Availability Impact

None

High

CVSS v3 Vector

Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Red Hat CVSS v3 Score Explanation

This vulnerability allows the bypass of some input filtering (so Integrity impact is rated Low). It does not enable access to additional information (so the Confidentiality impact is rated None) nor can it modify the operations of Curl (so Availability impact is rated None). From the perspective of the operating system or an even larger product using the OS, without the presence of additional vulnerabilities in telnet, the impact of this flaw simply would not be noticed.

This vulnerability allows the bypass of some input filtering (so Integrity impact is rated Low). It does not enable access to additional information (so the Confidentiality impact is rated None) nor can it modify the operations of Curl (so Availability impact is rated None). From the perspective of the operating system or an even larger product using the OS, without the presence of additional vulnerabilities in telnet, the impact of this flaw simply would not be noticed.

Acknowledgements

Red Hat would like to thank Daniel Stenberg and Harry Sintonen for reporting this issue.

Frequently Asked Questions

Why is Red Hat's CVSS v3 score or Impact different from other vendors?

For open source software shipped by multiple vendors, the CVSS base scores may vary for each vendor's version depending on the version they ship, how they ship it, the platform, and even how the software is compiled. This makes scoring of vulnerabilities difficult for third-party vulnerability databases such as NVD that only provide a single CVSS base score for each vulnerability. Red Hat scores reflect how a vulnerability affects our products specifically.

For more information, see https://access.redhat.com/solutions/762393.

My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?

  • "Under investigation" doesn't necessarily mean that the product is affected by this vulnerability. It only means that our Analysis Team is still working on determining whether the product is affected and how it is affected.
  • The term "Affected" means that our Analysis team has determined that this product, such as Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to address this issue in the near future. This includes all minor releases of this product unless noted otherwise in the Statement text.

What can I do if my product is listed as "Will not fix"?

A "will not fix" status means that a fix for an affected product version is not planned or not possible due to complexity, which may create additional risk.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Upgrade to a supported product version that includes a fix for this vulnerability (recommended).
  • Apply a mitigation (if one exists).
  • Open a support case to request a prioritization of releasing a fix for this vulnerability.

What can I do if my product is listed as "Fix deferred"?

A deferred status means that a fix for an affected product version is not guaranteed due to higher-priority development work.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Apply a mitigation (if one exists).
  • Open a support case to request a prioritization of releasing a fix for this vulnerability.
  • Red Hat Engineering focuses on addressing high-priority issues based on their complexity or limited lifecycle support. Therefore, lower-priority issues will not receive immediate fixes.

What is a mitigation?

A mitigation is an action that can be taken to reduce the impact of a security vulnerability, without deploying any fixes.

I have a Red Hat product but it is not in the above list, is it affected?

The listed products were found to include one or more of the components that this vulnerability affects. These products underwent a thorough evaluation to determine their affectedness by this vulnerability. Note that layered products (such as container-based offerings) that consume affected components from any of the products listed in this table may be affected and are not represented.

Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?

In order to maintain code stability and compatibility, Red Hat usually does not rebase packages to entirely new versions. Instead, we backport fixes and new features to an older version of the package we distribute. This can result in some security scanners that only consider the package version to report the package as vulnerable. To avoid this, we suggest that you use an approved vulnerability scanner from our Red Hat Vulnerability Scanner Certification program.

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