CVE-2020-28949
CVE-2020-28949 is a security flaw in PEAR Archive_Tar. Attackers can run their own code on PEAR Archive_Tar. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 25 Aug 2022.[1]
PEAR Archive_Tar is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. PEAR has published a fix or advice.
Description
CISA calls it a deserialization of untrusted data in PEAR Archive_Tar. In its words: “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.”[1]
The underlying weakness is CWE-74, in MITRE’s list of common software weaknesses.[2]
It scores 7.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; PEAR’s advisory has them[3]. CISA names the product as PEAR Archive_Tar.
Most families won’t have PEAR Archive_Tar; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 25 Aug 2022, 644 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 15 Sep 2022 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 85%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
PEAR has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]
- Check whether you use it.PEAR Archive_Tar is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 15 Sep 2022 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 7.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 85%.[4] |
See also
Other PEAR Archive_Tar flaws
- CVE-2020-36193: improper link resolution ·
Similar flaws
- CVE-2025-20337, Cisco Identity Services Engine: injection ·
- CVE-2025-20281, Cisco Identity Services Engine: injection ·
- CVE-2022-43769, Hitachi Vantara Pentaho Business Analytics (BA) Server: pentaho BA server special element injection ·
- CVE-2023-22527, Atlassian Confluence Data Center and Server: template injection ·
- CVE-2022-35914, Teclib GLPI: remote code execution ·
Added the same day
- CVE-2022-26352, dotCMS: unrestricted upload of file ·
- CVE-2022-24706, Apache CouchDB: insecure default initialization of resource ·
- CVE-2022-24112, Apache APISIX: authentication bypass ·
- CVE-2022-22963, VMware Tanzu Spring Cloud: function remote code execution ·
- CVE-2022-2294, WebRTC: heap buffer overflow ·
References
- ^ Cybersecurity and Infrastructure Security Agency. “PEAR Archive_Tar Deserialization of Untrusted Data Vulnerability”. Known Exploited Vulnerabilities Catalog, added 25 Aug 2022.
- ^ National Institute of Standards and Technology. “CVE-2020-28949 Detail”. National Vulnerability Database, published 19 Nov 2020.
- ^ PEAR. Advisories and fixes: pear.php.net, drupal.org, access.redhat.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.846, percentile 99.7, 31 Oct 2026.
- CVE Program. “CVE-2020-28949”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.