How severe is CVE-2021-26599?

CVE-2021-26599 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-26599?

CVE-2021-26599 affects the following packages: impresscms/impresscms (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2021-26599?

Update impresscms/impresscms to 1.4.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-26599 is resolved across your whole dependency graph.

How do I detect CVE-2021-26599 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-2021-26599 if there is no patch (or I can't update yet)?

Until you can upgrade, make sure every query built from user input uses parameterised statements or a prepared-statement API rather than string concatenation, and reduce the database account's privileges so an injected query cannot read or alter data beyond what the feature needs.

Is CVE-2021-26599 actively exploited in the wild?

Yes. There are 4 known exploit references for CVE-2021-26599, 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-2021-26599?

CVE-2021-26599 has an EPSS (Exploit Prediction Scoring System) score of 21.0%, placing it in the 98th 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-2021-26599?

CVE-2021-26599 is classified as SQL Injection (CWE-89). 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.

Is there exploit tooling available for CVE-2021-26599?

A Nuclei detection template exists for CVE-2021-26599, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2021-26599 published, and has it been updated?

CVE-2021-26599 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

CRITICAL severity

CVE-2021-26599 — impresscms

CRITICAL

CVE-2021-26599 is a critical-severity (CVSS 9.8) SQL Injection vulnerability in impresscms/impresscms. 4 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.

SQL Injection in ImpressCMS

Also known asGHSA-jc4v-vvg6-xg78

Published

Mar 28, 2022

Updated

Oct 24, 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 ↗

21.0%probability of exploitation in next 30 days

Moderate Risk0.00%

Lower risk than most CVEs98th percentile — riskier than 98% 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 include/findusers.php groups SQL Injection.

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

< 1.4.4

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-50839webappsphp

ImpressCMS 1.4.2 - Remote Code Execution (RCE)

by Egidio Romano · Mar 30, 2022

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 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-2021-26599 is resolved across your whole dependency graph.
Workarounds
Until you can upgrade, make sure every query built from user input uses parameterised statements or a prepared-statement API rather than string concatenation, and reduce the database account's privileges so an injected query cannot read or alter data beyond what the feature needs.

How to detect CVE-2021-26599

A community-maintained Nuclei template exists for this CVE. You can scan for it directly:

nuclei -id cve-2021-26599 -u https://target

Template: ImpressCMS < 1.4.3 - SQL Injection
Severity: high
Impact: Unauthenticated attackers can execute arbitrary SQL queries via SQL injection, potentially extracting sensitive database contents or modifying data.
Remediation: Update ImpressCMS to version 1.4.3 or later.

Template by ProjectDiscovery nuclei-templates (ritikchaddha), MIT licensed. View the full template. Scan only systems you are authorised to test.

Frequently Asked Questions

ImpressCMS before 1.4.3 allows include/findusers.php groups SQL Injection.

O3 Security · Impact-Aware SCA

Is CVE-2021-26599 in your dependencies?

Find it across Packagist, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

9.8/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Raw vector

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

CWE Classification

Weaponization

Timeline

Disclosed

Mar 28, 2022

First exploit

Mar 30, 2022

2 days after disclosure — rapid exploitation

Last updated

Oct 24, 2026

Identifiers

CVE-2021-26599

GHSA-jc4v-vvg6-xg78

References

Advisorynvd.nist.gov · CVE 2021 26599 Reporthackerone.com Webgithub.com · v1.4.3 Packagegithub.com · impresscms Evidencekarmainsecurity.com · KIS 2022 04 Evidencepacketstormsecurity.com · ImpressCMS 1.4.2 SQL Injection Evidenceseclists.org

Related vulnerabilities

This CVE is critical severity — higher than any of the other 8 CVEs affecting impresscms/impresscms (highest there: high).

CVE-2023-37785CVE-2018-13983CVE-2014-4036CVE-2014-1836CVE-2010-4616CVE-2022-26986CVE-2021-26598CVE-2021-26601

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 24, 2026

CVE-2021-26599 — impresscms

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

How to detect CVE-2021-26599

Frequently Asked Questions

Is CVE-2021-26599 in your dependencies?