CVE-2020-28949

PEAR Archive_Tar: Deserialization of Untrusted Data

As of , CVE-2020-28949 in PEAR Archive_Tar is on CISA's list of exploited vulnerabilities: CISA listed it on . Our patch-first group: Patch this week.

Exploited
Yes: CISA listed it on 25 August 2022
US federal deadline
15 September 202221 days after CISA listed it. US federal civilian agencies must fix it by then.
Used in ransomware campaigns
Not known to CISA
EPSS score
0.85Higher than 99% of the CVEs EPSS scores. EPSS estimates the chance of exploitation activity in the next 30 days.
EPSS when listed
0.64 on 25 August 2022EPSS on the day CISA listed it.
Public exploit
1 Metasploit module
Fix
Vendor advice: pear.php.netLinks below, from CISA's entry.

What CISA says to do

Apply updates per vendor instructions.

CISA's required action

What the flaw is

PEAR Archive_Tar allows an unserialization attack because phar: is blocked but PHAR: is not blocked. PEAR stands for PHP Extension and Application Repository and it is an open-source framework and distribution system for reusable PHP components with known usage in third-party products such as Drupal Core and Red Hat Linux.

CISA's description

Archive_Tar through 1.4.10 has :// filename sanitization only to address phar attacks, and thus any other stream-wrapper attack (such as file:// to overwrite files) can still succeed.

The CVE record's description, from mitre

CVE published
19 November 2020
Assigned by
mitre
CVSS
7.8 High (CVSS 3.1, from CISA-ADP)
CWE-74
Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
CISA SSVC, exploitation
active
CISA SSVC, automatable
no
CISA SSVC, technical impact
total

Timeline

  1. The CVE record was published.
  2. CISA added it to its list of exploited vulnerabilities.
  3. The US federal deadline to fix it.

Public exploits

Facts from Metasploit's module list and Exploit-DB's index; we never copy exploit code.

  • Metasploit: PEAR Archive_Tar 1.4.10 Arbitrary File Writeexploit module, rank excellent

Archive_Tar: other exploited entries

VulnerabilityProductOur groupListedDeadlineEPSS
CVE-2020-36193Improper Link ResolutionPEAR Archive_TarPatch this weekEPSS 0.710.71

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