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Actively exploited

CVE-2020-28949 PEAR Archive_Tar Deserialization of Untrusted Data Vulnerability

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.

From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.

Our Assessment

Should You Worry?

Patch urgentlyCybergen assessment
  • CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 25 Aug 2022.
  • Rated High severity (CVSS 7.8, scored by CISA).
  • It has been in the catalogue for 1,534 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

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.

From Watch to Action

What To Do Now

  1. 1

    Find it

    Search your asset inventory and external attack surface for PEAR Archive_Tar. Include cloud images, appliances and anything a supplier runs for you.

    Attack Surface Management
  2. 2

    Fix it

    Apply updates per vendor instructions.

    Vulnerability Management
  3. 3

    Hunt for compromise

    If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.

    Incident Response
  4. 4

    Prove it is fixed

    Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.

    Penetration Testing

Vendor Advisories

Regulation

The Compliance Clock

Cyber EssentialsRated high, so if it affects devices in your Cyber Essentials scope, the update must be installed within 14 days of the vendor releasing it.NIS2If exploitation causes a significant incident, essential and important entities owe their CSIRT an early warning within 24 hours and a notification within 72 hours.DORAFinancial entities must classify ICT incidents and send an initial notification for a major incident within strict deadlines, with exploited flaws a common cause.US federal (BOD 22-01)Federal civilian agencies had until 15 Sep 2022 to remediate. A sensible benchmark for everyone else.

General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.

Stay Ahead

More Exploited PEAR Flaws

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CVE-2020-36193PEAR Archive_Tar Improper Link Resolution VulnerabilityAdded 25 Aug 2022

All 2 exploited PEAR vulnerabilities

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Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2020-28949
  3. CVE record: CVE-2020-28949
  4. FIRST EPSS
  5. pear.php.net/bugs/bug.php?id=27002, https://www.drupal.org/sa-core-2020-013, https://access.redhat.c
  6. github.com/pear/Archive_Tar/issues/33
  7. drupal.org/sa-core-2020-013
  8. lists.debian.org/debian-lts-announce/2020/11/msg00045.html
  9. lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4V35LBRM6HB
  10. lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NBYZSHYTIOB
  11. lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KWM4CTMEGAC
  12. lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5KSFM672XW3