CVE-2023-40555 | WordPress Flatsome Theme <= 3.17.5 is vulnerable to PHP Object Injection

Deserialization of Untrusted Data vulnerability in UX-themes Flatsome | Multi-Purpose Responsive WooCommerce Theme.This issue affects Flatsome | Multi-Purpose Responsive WooCommerce Theme: from n/a through 3.17.5.

Published: 2023-12-20 Last update: 2026-04-28 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-40555 is rated Moderate Risk (45.6/100): CVSS High severity, with low exploitation likelihood (EPSS 0.15%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-40555

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-11-21 0.47% 0.15% -0.32%
2 2025-11-18 0.15% 0.47% +0.32%
3 2025-05-10 — 0.15% —

Full EPSS history (12 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-40555

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.3 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 3.7 [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]

Weakness enumeration for CVE-2023-40555

GitHub Security Advisory for CVE-2023-40555

GHSA-9fmf-6xvc-qw23 · Severity: high — Deserialization of Untrusted Data vulnerability in UX-themes Flatsome | Multi-Purpose Responsive...

Affected software / configurations for CVE-2023-40555

Vendor Product Version Raw CPE
uxthemes flatsome < 3.17.6 cpe:2.3:a:uxthemes:flatsome:*:*:*:*:*:wordpress:*:*

References for CVE-2023-40555

cvelogic Threat Intelligence