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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 15 Sep 2022.
Archive TarApplication · PHP

CVE-2020-28949

HIGH · 7.8 CVSS v3.1 Published 2020-11-19
Fix available
A fix is available. Upgrade to 1.4.12 / 7.75 or later.
See remediation →
97/100
Remediation priority · Urgent
In the wild High EPSS Public exploit No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Archive_Tar through 1.4.10 performed incomplete filename sanitization that only addressed phar:// stream wrappers to prevent PHP object injection attacks. The library failed to sanitize other dangerous stream wrappers such as file://, allowing crafted malicious tar archives to overwrite arbitrary files on the server when extracted.

MitigationUpgrade Archive_Tar to version 1.4.14 or later which implements comprehensive stream wrapper sanitization. As a temporary measure, validate all extracted file paths at the application layer before extraction.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Archive TarApplication
Affected:< 1.4.12
Debian LinuxOperating system
Affected:= 9.0= 10.0
FedoraOperating system
Affected:= 32= 33= 34= 35
DrupalCMS
Affected:>= 7.0, < 7.75>= 8.0.0, < 8.9.10>= 8.8.0, < 8.8.12>= 9.0.0, < 9.0.9

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Archive_Tar PHP library version
    Run 'composer show pear/archive_tar' or inspect the file PEAR/Archive/Tar.php and look for the version constant at the top of the file
    Affected if The version is less than 1.4.12 (or if no version is displayed and the file date is older than November 2020)
  2. Identify if Drupal uses Archive_Tar
    Check if the Drupal site uses the tar library: look for the 'tar' library in Drupal's /libraries directory, or run 'drush pm:list' to see if Archive_Tar is a dependency
    Affected if Drupal is installed and relies on an unpatched Archive_Tar version below 1.4.12
  3. Determine Drupal core version
    Run 'drush status' or inspect the file CHANGELOG.txt in the Drupal root directory
    Affected if Drupal version is 7.0-7.74, 8.0.0-8.9.9, 8.8.0-8.8.11, or 9.0.0-9.0.8
  4. Check OS version on Debian or Fedora
    Run 'cat /etc/debian_version' for Debian or 'cat /etc/fedora-release' for Fedora
    Affected if The OS is Debian 9.0 or 10.0, or Fedora 32, 33, 34, or 35
  5. Verify if application processes untrusted tar archives
    Review application code that calls Archive_Tar::extract() or similar extraction methods, checking if the tar input originates from untrusted sources (user uploads, external APIs, network sources)
    Affected if The application extracts tar archives from untrusted sources using the vulnerable Archive_Tar library

You are affected if your system uses Archive_Tar below version 1.4.12 AND processes tar archives from untrusted sources, particularly on the listed Drupal or OS versions.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.4.12 / 7.75 / 8.8.12 or later
Fixed in 1.4.127.758.8.12
Interim mitigation

Upgrade Archive_Tar to version 1.4.14 or later which implements comprehensive stream wrapper sanitization. As a temporary measure, validate all extracted file paths at the application layer before extraction.

Recommended fix High confidence

Archive_Tar >= 1.4.12 (or Drupal 7.75+/8.8.12+/8.9.10+/9.0.9+)

  1. 1. Identify the application or dependency that uses the Archive_Tar PEAR package
  2. 2. For PHP/PEAR environments: Run 'pear upgrade Archive_Tar' or use composer to update the pear/archive_tar package to version 1.4.12 or later
  3. 3. For Drupal 7.x: Upgrade to Drupal 7.75 or later
  4. 4. For Drupal 8.8.x: Upgrade to Drupal 8.8.12 or later
  5. 5. For Drupal 8.9.x: Upgrade to Drupal 8.9.10 or later
  6. 6. For Drupal 9.0.x: Upgrade to Drupal 9.0.9 or later
  7. 7. Verify the installed Archive_Tar version matches or exceeds 1.4.12 using 'pear list Archive_Tar' or checking composer.lock
  8. 8. Test the application functionality to ensure the upgrade does not break existing tar extraction operations
Caveat Archive_Tar 1.4.12 is a patch release focused on security; minimal breaking changes expected. Always test in staging first.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Archive Tar Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing4.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,900
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2020-28949 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data