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Photolia EUVDEUVD-2026-96530

| CVE-2026-78535 CRITICAL
Deserialization of Untrusted Data (CWE-502)
2026-10-10 Patchstack GHSA-rfhw-cf7w-cjpq
9.8
CVSS 3.1 · Vendor: Patchstack
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Reach Photolia theme endpoint
  2. Delivery
    Submit malicious serialized PHP object
  3. Exploit
    unserialize() instantiates object
  4. Execution
    Trigger POP gadget chain
  5. Impact
    Execute code / tamper with site

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A08:2025 - Software or Data Integrity Failures
ASVS 5.0
V1 - Encoding and Sanitization Safe deserialization, type allowlists
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Initial Access

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

The vulnerable Photolia theme (versions <= 1.0.3) must be installed and active on a WordPress site, and the attacker must reach the theme code path that passes untrusted input to PHP unserialize(). Per the CVSS vector (PR:N/UI:N), no authentication or user interaction is required, so default installations are exposed over the network. The key LIMITING factor inherent to CWE-502 object injection is that achieving code execution or other meaningful impact requires a usable POP gadget chain present in WordPress core or a co-installed plugin/theme; absent a reachable gadget chain, realized impact may be reduced. Exploitation is further bounded to the specific population of sites running this theme at or below 1.0.3.

Impact

All signals point to a high-severity but likely low-to-moderate real-world priority. The Patchstack-supplied CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N, C:H/I:H/A:H, score 9.8) describes a network-reachable, unauthenticated flaw with full confidentiality/integrity/availability impact - the theoretical worst case for a web application. However, the only intelligence source is a single Patchstack advisory; there is NO EPSS score, NO CISA KEV listing, and NO public exploit referenced, so no public exploit identified at time of analysis. The practical caveat with CWE-502 PHP Object Injection is that the 9.8 rating assumes a usable POP (property-oriented programming) gadget chain is reachable - such chains are frequently present in WordPress core or co-installed plugins, but the advisory does not confirm a working chain in Photolia itself, so the maximal impact is plausible but unverified. SSVC inputs (exploitation status, automatable, technical impact) were not provided and cannot be assessed. Net: treat as a patch-now item for any site running Photolia <= 1.0.3, but the limited product footprint plus the absence of exploitation and EPSS signals argue against emergency, fleet-wide prioritization.

Exploit ScenarioDerived

A remote, unauthenticated attacker sends a crafted request to a Photolia theme endpoint that passes attacker-controlled data to PHP unserialize(). By supplying a serialized object that triggers an existing POP gadget chain (in WordPress core or an installed plugin), the attacker can achieve file operations or remote code execution on the host. No public proof-of-concept is referenced, so weaponization would require identifying a viable gadget chain for the target environment.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.
No patch listed yet 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 10, 2026

PHP object injection in the Photolia WordPress theme (versions <= 1.0.3) allows unauthenticated remote attackers to trigger deserialization of untrusted data, potentially leading to code execution, file manipulation, or data theft if a usable POP gadget chain exists in the WordPress environment. Although rated CVSS 9.8, the practical risk is tempered by the requirement for a reachable gadget chain in core or co-installed components, and no public exploit has been identified at time of analysis. Site owners should treat this as high severity but prioritize based on exposure.

RemediationAI

No vendor-released patch has been identified at time of analysis. The most effective immediate mitigation is to remove or deactivate the Photolia theme from all WordPress installations; if the theme is essential for site design, ensure a safe alternative theme is ready before removal to avoid site breakage. As a compensating control, deploy web application firewall (WAF) rules that detect and block PHP object injection attempts targeting the theme's endpoints, though obfuscated payloads may bypass such rules. Additionally, reduce the attack surface by removing unused plugins and themes to limit available POP gadget chains, but note this does not eliminate the vulnerability. Monitor the Patchstack advisory at https://patchstack.com/database/wordpress/theme/photolia/vulnerability/wordpress-photolia-theme-1-0-3-php-object-injection-vulnerability?_s_id=cve for updates and apply a patch as soon as it is released.

Affected VersionsENISA

Photolia n/a ≤1.0.3

Affected Packages

euvd photolia no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The Photolia theme by ThemeREX for WordPress contains a PHP object injection vulnerability (CWE-502) in versions up to and including 1.0.3. The flaw arises from passing user-supplied input to PHP's unserialize() function without proper validation, allowing an unauthenticated attacker to inject arbitrary serialized objects. Successful exploitation depends on the presence of a usable POP (Property-Oriented Programming) gadget chain within WordPress core or any co-installed plugin or theme, which could then be leveraged to achieve remote code execution, arbitrary file deletion, or sensitive data exposure. The CPE cpe:2.3:a:themerex:photolia:*:*:*:*:*:*:*:* indicates the vendor's theme, and the Patchstack advisory confirms the affected version range. This vulnerability class is particularly dangerous because it can be triggered without authentication, but its realized impact is inherently limited by the available gadget chain.

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Severity by source

Vendor (Patchstack) PRIMARY 9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI 9.8 CRITICAL

Unauthenticated network-reachable unserialize() of attacker input (AV:N/AC:L/PR:N/UI:N); object injection with a reachable gadget chain yields RCE-level C:H/I:H/A:H.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (Patchstack).

CVSS VectorVendor: Patchstack

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionCVE.org

Unauthenticated PHP Object Injection in Photolia <= 1.0.3 versions.

Executive ViewAI

Why It Matters

The Photolia WordPress theme (versions 1.0.3 and earlier) carries a critical PHP object injection flaw that could let an attacker execute code, alter files, or exfiltrate data from any site running it. Practical risk varies by installation because exploitation depends on a usable gadget chain being present in WordPress core or co-installed components, and no public exploit has been identified at time of analysis. Leadership should care because a successful compromise of a public-facing website can expose customer data, deface the brand, and serve as an entry point into broader corporate networks.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations: deactivate or remove the Photolia theme (versions <= 1.0.3), deploy WAF virtual patching for PHP object injection, enable file-integrity and deserialization monitoring, restrict file system and outbound network permissions, and audit WordPress core and co-installed components for exploitable gadget chains.

Threat Intelligence Overview

EPSS Score
0.3%
Top 75% exploitable
Prevalence
Low
niche WordPress photography theme, limited production deployment
Data Quality
6 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity CRITICAL
CISA KEV No
Public POC No
EPSS 0.3%
Patch available No
Active threat No
Deciding rule
CRITICAL severity
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
Yes
Human Impact
High
Technical Impact
Total

Priority Score

49
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +49
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Insecure deserialization occurs when an application converts serialized data (a stream of bytes representing an object's state) back into a living object without proper validation.

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