Cyber Resilience

CVE-2026-40521

HighPublic PoC

Published: 29 June 2026

Published
29 June 2026
Modified
30 June 2026
KEV Added
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Patch
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CVSS Score v4 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0063 45.7th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-40521 is a high-severity Path Traversal (CWE-22) vulnerability in Jivasecurity (inferred from references). Its CVSS base score is 8.7 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 45.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

OWASP Top 10 for Web (2025)

A01:2025 Broken Access Control

EU & UK References

Vulnerability details

FrontAccounting before 2.4.20 contains a path traversal vulnerability in the attachment upload handler that allows authenticated attackers to execute arbitrary code by uploading files with traversal sequences in the unique_name parameter. Attackers can supply path traversal sequences ../../../shell.php to write…

more

files outside the intended attachments directory into the web root, and by uploading PHP files without extension validation, achieve remote code execution as the web server user.

CWE(s)
CWE-22

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1505.003 Web Shell Persistence
Adversaries may backdoor web servers with web shells to establish persistent access to systems.
attack.mitre.org →
Why these techniques?

Path traversal in web app upload handler directly enables web shell deployment for RCE on public-facing server (T1190 + T1505.003).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2024-50648Shared CWE-22
CVE-2024-34854Shared CWE-22
CVE-2024-13545Shared CWE-22
CVE-2023-53979Shared CWE-22
CVE-2025-1661Shared CWE-22
CVE-2025-12382Shared CWE-22
CVE-2024-13409Shared CWE-22
CVE-2026-24478Shared CWE-22
CVE-2025-54438Shared CWE-22
CVE-2025-67684Shared CWE-22

Affected Assets

Jivasecurity
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inferred from references and description; NVD did not file a CPE for this CVE

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SI-10 Information Input Validation
addresses: CWE-22

Validates pathnames and filenames to prevent traversal outside intended directories.

References