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MEDIUM severity

Incorrect Access Control in ImpressCMSGHSA-48p3-xfvw-g59c

MEDIUMFix: ImpressCMS/impresscms#967

GHSA-48p3-xfvw-g59c is a medium-severity (CVSS 5.3) Improper Authentication 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.

Also known asCVE-2021-26598
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
4 known
Exploitation data as of Nov 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
10.5%probability of exploitation in next 30 days
Moderate Risk0.00%
Lower risk than most CVEs96th percentile — riskier than 96% of all scored CVEsHighest risk
0.00%31.9%63.8%95.7%76.1%10.5%May 26Sep 26Nov 26

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 has Incorrect Access Control because include/findusers.php allows access by unauthenticated attackers (who are, by design, able to have a security token).

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐘Packagistimpresscms/impresscmsall versions1.4.3composer require impresscms/impresscms:^1.4.3

Affected Products

1 product · 1 configurations
Application
impresscmsimpresscms
< 1.4.3
range
Exploits & PoCs
4

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

Detection & mitigation playbook

Open-source dependency
  1. 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.

  2. Fix

    Update impresscms/impresscms to 1.4.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-48p3-xfvw-g59c is resolved across your whole dependency graph.

  3. Workarounds

    Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

How to detect GHSA-48p3-xfvw-g59c

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

nuclei -id ghsa-48p3-xfvw-g59c -u https://target
Template
ImpressCMS <1.4.3 - Incorrect Authorization
Severity
medium
Impact
An attacker can bypass authorization and gain unauthorized access to sensitive information or perform unauthorized actions.
Remediation
Upgrade to ImpressCMS version 1.4.3 or later to fix the vulnerability.

Template by ProjectDiscovery nuclei-templates (gy741, pdteam), MIT licensed. View the full template. Scan only systems you are authorised to test.

Frequently Asked Questions

ImpressCMS before 1.4.3 has Incorrect Access Control because include/findusers.php allows access by unauthenticated attackers (who are, by design, able to have a security token).
O3 Security · Impact-Aware SCA

Is GHSA-48p3-xfvw-g59c in your dependencies?

Find it across Packagist, including transitive dependencies.

Incorrect Access Control in ImpressCMS (Medium 5.3)