How severe is CVE-2018-1000888?

CVE-2018-1000888 has a CVSS score of 8.8/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2018-1000888?

CVE-2018-1000888 affects the following packages: pear/archive_tar (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2018-1000888?

Update pear/archive_tar to 1.4.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-1000888 is resolved across your whole dependency graph.

How do I detect CVE-2018-1000888 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pear/archive_tar, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2018-1000888 if there is no patch (or I can't update yet)?

Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Is CVE-2018-1000888 actively exploited in the wild?

Yes. There are 4 known exploit references for CVE-2018-1000888, including 1 documented proof-of-concept exploit on Exploit-DB and 3 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2018-1000888?

CVE-2018-1000888 has an EPSS (Exploit Prediction Scoring System) score of 19.1%, placing it in the 97th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score warrants monitoring and prompt remediation.

What type of vulnerability is CVE-2018-1000888?

CVE-2018-1000888 is classified as Deserialization of Untrusted Data (CWE-502). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2018-1000888 published, and has it been updated?

CVE-2018-1000888 was published on December 28, 2018 and was last updated on March 15, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘

🐘 Packagist

Not in CISA KEV

HIGH severity

CVE-2018-1000888 — archive_tar

HIGHFix: pear/Archive_Tar@59ace12

CVE-2018-1000888 is a high-severity (CVSS 8.8) Deserialization of Untrusted Data vulnerability in pear/archive_tar. 4 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for pear/archive_tar — see the affected versions and patch details below.

Archive_Tar contains Potential RCE if filename starts with phar://

Also known asGHSA-3q76-jq6m-573p

Published

Dec 28, 2018

Updated

Mar 15, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

4 known

Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

19.1%probability of exploitation in next 30 days

Moderate Risk0.00%

Lower risk than most CVEs97th percentile — riskier than 97% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐘pear/archive_tar

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

PEAR Archive_Tar version 1.4.3 and earlier contains a CWE-502, CWE-915 vulnerability in the Archive_Tar class. There are several file operations with $v_header['filename'] as parameter (such as file_exists, is_file, is_dir, etc). When extract is called without a specific prefix path, we can trigger unserialization by crafting a tar file with phar://[path_to_malicious_phar_file] as path. Object injection can be used to trigger destruct in the loaded PHP classes, e.g. the Archive_Tar class itself. With Archive_Tar object injection, arbitrary file deletion can occur because @unlink($this->_temp_tarname) is called. If another class with useful gadget is loaded, it may possible to cause remote code execution that can result in files being deleted or possibly modified. This vulnerability appears to have been fixed in 1.4.4.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`pear/archive_tar`	all versions	1.4.4`composer require pear/archive_tar:^1.4.4`

Affected Products

3 products · 6 configurations

ubuntu linuxcanonical

3 versions

16.0418.0418.10

debian linuxdebian

2 versions

8.09.0

Application

pear archive tarphp

≤ 1.4.3

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

EDB-46108webappsphp

PEAR Archive_Tar < 1.4.4 - PHP Object Injection

by Fariskhi Vidyan · Jan 10, 2019

Exploit-DB Source

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pear/archive_tar, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update pear/archive_tar to 1.4.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-1000888 is resolved across your whole dependency graph.
Workarounds
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Frequently Asked Questions

PEAR Archive_Tar version 1.4.3 and earlier contains a CWE-502, CWE-915 vulnerability in the Archive_Tar class. There are several file operations with `$v_header['filename']` as parameter (such as file_exists, is_file, is_dir, etc). When extract is called without a specific prefix path, we can trigger unserialization by crafting a tar file with `phar://[path_to_malicious_phar_file]` as path. Object injection can be used to trigger destruct in the loaded PHP classes, e.g. the Archive_Tar class itself. With Archive_Tar object injection, arbitrary file deletion can occur because `@unlink($this->_t

O3 Security · Impact-Aware SCA

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