SB2020120936 - Ubuntu update for curl 

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Main Vulnerability Database SB2020120936

SB2020120936 - Ubuntu update for curl

Published: December 9, 2020 Updated: April 23, 2025

Security Bulletin ID SB2020120936
Severity
Medium
Patch available
YES
Number of vulnerabilities 4
Exploitation vector Remote access
Highest impact Data manipulation

Breakdown by Severity

Medium 50% Low 50%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 4 secuirty vulnerabilities.


1) Expired pointer dereference (CVE-ID: CVE-2020-8231)

The vulnerability allows an attacker to gain access to sensitive information.

The vulnerability exists due to expired pointer dereference error for CURLOPT_CONNECT_ONLY connections that may lead to information disclosure. If the application is using the CURLOPT_CONNECT_ONLY option to check if the website is accessible, an attacker might abuse this feature and force the application to re-use expired connection and send data intended to another connection to attacker controlled server.


2) Information disclosure (CVE-ID: CVE-2020-8284)

The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists due to the way cURL handles PASV responses. A remote attacker with control over malicious FTP server can use the PASV response to trick curl into connecting back to a given IP address and port, and this way potentially make curl extract information about services that are otherwise private and not disclosed, for example doing port scanning and service banner extractions.


3) Uncontrolled Recursion (CVE-ID: CVE-2020-8285)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due tu uncontrolled recursion when processing FTP responses within the wildcard matching functionality, which allows a callback (set with <a href="https://curl.se/libcurl/c/CURLOPT_CHUNK_BGN_FUNCTION.html">CURLOPT_CHUNK_BGN_FUNCTION</a>) to return information back to libcurl on how to handle a specific entry in a directory when libcurl iterates over a list of all available entries. A remote attacker who controls the malicious FTP server can trick the victim to connect to it and crash the application, which is using the affected libcurl version.


4) Improper Check for Certificate Revocation (CVE-ID: CVE-2020-8286)

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to incorrectly implemented checks for OCSP stapling. A remote attacker can provide a fraudulent OCSP response that would appear fine, instead of the real one.


Remediation

Install update from vendor's website.

References