How severe is CVE-2021-26601?

CVE-2021-26601 has a CVSS score of 8.1/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-26601?

CVE-2021-26601 affects the following packages: impresscms/impresscms (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2021-26601?

Update impresscms/impresscms to 1.4.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-26601 is resolved across your whole dependency graph.

How do I detect CVE-2021-26601 in my Packagist dependencies?

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

How do I mitigate CVE-2021-26601 if there is no patch (or I can't update yet)?

Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Is CVE-2021-26601 actively exploited in the wild?

Yes. There are 3 known exploit references for CVE-2021-26601, including 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-2021-26601?

CVE-2021-26601 has an EPSS (Exploit Prediction Scoring System) score of 3.2%, placing it in the 88th 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 indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-26601?

CVE-2021-26601 is classified as Path Traversal (CWE-22). 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-2021-26601 published, and has it been updated?

CVE-2021-26601 was published on March 28, 2022 and was last updated on October 24, 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-2021-26601 — impresscms

HIGHFix: ImpressCMS/impresscms#915

CVE-2021-26601 is a high-severity (CVSS 8.1) Path Traversal vulnerability in impresscms/impresscms. 3 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for impresscms/impresscms — see the affected versions and patch details below.

Path Traversal in ImpressCMS

Also known asGHSA-4q96-9f63-p7jj

Published

Mar 28, 2022

Updated

Oct 24, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

3 known

Exploitation data as of Nov 2, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

3.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs88th percentile — riskier than 88% 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

🐘impresscms/impresscms

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

ImpressCMS before 1.4.3 allows libraries/image-editor/image-edit.php image_temp Directory Traversal.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`impresscms/impresscms`	all versions	1.4.3`composer require impresscms/impresscms:^1.4.3`

Affected Products

1 product · 1 configurations

Application

impresscmsimpresscms

< 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.

ImpressCMS before 1.4.3 allows libraries/image-editor/image-edit.php ima…

packetstormsecurity.comNVDMar 2022

Report on hackerone.com

hackerone.comNVDMar 2022

Report on seclists.org

seclists.orgNVDMar 2022

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for impresscms/impresscms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update impresscms/impresscms to 1.4.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-26601 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Frequently Asked Questions

ImpressCMS before 1.4.3 allows libraries/image-editor/image-edit.php image_temp Directory Traversal.

O3 Security · Impact-Aware SCA

Is CVE-2021-26601 in your dependencies?

Find it across Packagist, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

8.1/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

High

Raw vector

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

CWE Classification

CWE-22Path Traversal

Weaponization

No Nuclei template or Metasploit module yet. 3 public proof-of-concept references are listed on this page.

Timeline

Disclosed

Mar 28, 2022

First exploit

Mar 30, 2022

3 days after disclosure — rapid exploitation

Last updated

Oct 24, 2026

Identifiers

CVE-2021-26601

GHSA-4q96-9f63-p7jj

References

Advisorykarmainsecurity.com · KIS 2022 02 Advisorynvd.nist.gov · CVE 2021 26601 Webgithub.com Webgithub.com Webgithub.com · v1.4.3 Packagegithub.com · impresscms Evidencepacketstormsecurity.com · ImpressCMS 1.4.2 Path Traversal Evidenceseclists.org Evidencehackerone.com

Related vulnerabilities

This CVE is high severity; 2 of 8 other CVEs affecting impresscms/impresscms are rated as high or higher (top: critical).

CVE-2023-37785CVE-2018-13983CVE-2014-4036CVE-2014-1836CVE-2010-4616CVE-2022-26986CVE-2021-26598CVE-2021-26599

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 24, 2026