CyberSecBulletin
CVE-2020-28949Exploited in the wildNVD status: Analyzed

PEAR Archive_Tar Deserialization of Untrusted Data

Published Updated By the CyberSecBulletin desk

CVE-2020-28949 is a high-severity vulnerability in Archive Tar from PHP, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists version 1.4.12 as the first without the flaw, so updating Archive Tar to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on August 25, 2022, which means attacks have been observed in the wild.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Update Archive Tar to 1.4.12 or a later version.
  2. Update Drupal to 7.75 or 8.9.10 or 8.8.12 or 9.0.9, whichever matches your release line, or a later version.
  3. CISA's required action: Apply updates per vendor instructions.
  4. Read the advisory on github.com for workarounds and exact fixed builds.
  5. Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.

Affected products and versions

VendorProductAffected versionsFixed in
PHPArchive Tarbefore 1.4.121.4.12
DebianDebian Linux9.0; 10.0Not stated
Fedora ProjectFedora32; 33; 34; 35Not stated
DrupalDrupal7.0 up to, but not including, 7.75; 8.0.0 up to, but not including, 8.9.10; 8.8.0 up to, but not including, 8.8.12; 9.0.0 up to, but not including, 9.0.97.75, 8.9.10, 8.8.12, 9.0.9

Version data comes from NVD's product matching. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
RequiredA user must take an action such as opening a file or link.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

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

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighNVD
CVSS 3.17.8HighCISA (ADP)
CVSS 2.06.8MediumNVD

Official 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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

Timeline

  1. CVE record published.
  2. Added to CISA's Known Exploited Vulnerabilities catalogue.
  3. Deadline for US federal agencies to remediate, set by CISA.
  4. CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
  5. Record last changed materially (score, affected products, status or references).

References

Advisories

Third-party and government advisories

Technical write-ups (may include proof of concept)

Other vulnerabilities in Archive Tar

All Archive Tar vulnerabilities

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