CVE-2026-5217 | Optimole Plugin up to 4.2.2 on WordPress REST Endpoint optimizations sanitize_text_field cross site scripting

VDB-356952 · CVE-2026-5217 · EUVD-2026-21662 OPTIMOLE PLUGIN UP TO 4.2.2 ON WORDPRESS REST ENDPOINT OPTIMIZATIONS SANITIZE_TEXT_FIELD CROSS SITE SCRIPTING HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 5.7 $0-$5k 0.11 Summaryinfo A vulnerability categorized as problematic has been discovered in Optimole Plugin up to 4.2.2 on WordPress. This affects the function sanitize_text_field of the file /wp-json/optimole/v1/optimizations of the component REST Endpoint. The manipulation results in cross site scripting. This vulnerability is reported as CVE-2026-5217. The attack can be launched remotely. No exploit exists. Detailsinfo A vulnerability, which was classified as problematic, was found in Optimole Plugin up to 4.2.2 on WordPress. Affected is the function sanitize_text_field of the file /wp-json/optimole/v1/optimizations of the component REST Endpoint. The manipulation with an unknown input leads to a cross site scripting vulnerability. CWE is classifying the issue as CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. This is going to have an impact on integrity. CVE summarizes: The Optimole – Optimize Images | Convert WebP & AVIF | CDN & Lazy Load | Image Optimization plugin for WordPress is vulnerable to Stored Cross-Site Scripting in all versions up to, and including, 4.2.2. This is due to insufficient input sanitization and output escaping on the user-supplied 's' parameter (srcset descriptor) in the unauthenticated /wp-json/optimole/v1/optimizations REST endpoint. The endpoint validates requests using an HMAC signature and timestamp, but these values are exposed directly in the frontend HTML making them accessible to any visitor. The plugin uses sanitize_text_field() on the descriptor value of rest.php, which strips HTML tags but does not escape double quotes. The poisoned descriptor is then stored via transients (backed by the WordPress options table) and later retrieved and injected verbatim into the srcset attribute of tag_replacer.php without proper escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts into pages that will execute whenever a user accesses the injected page. The weakness was disclosed by Quốc Huy. The advisory is shared for download at wordfence.com. This vulnerability is traded as CVE-2026-5217 since 03/31/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1059.007. There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product. The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-21662). Productinfo Type WordPress Plugin Name Optimole Plugin Version 4.2.0 4.2.1 4.2.2 CPE 2.3info 🔒 🔒 🔒 CPE 2.2info 🔒 🔒 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv3info VulDB Meta Base Score: 5.7 VulDB Meta Temp Score: 5.7 VulDB Base Score: 4.3 VulDB Temp Score: 4.2 VulDB Vector: 🔒 VulDB Reliability: 🔍 CNA Base Score: 7.2 CNA Vector (Wordfence): 🔒 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Cross site scripting CWE: CWE-79 / CWE-94 / CWE-74 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Yes Availability: 🔒 Status: Not defined Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: no mitigation known Status: 🔍 0-Day Time: 🔒 Timelineinfo 03/31/2026 CVE reserved 04/11/2026 +11 days Advisory disclosed 04/11/2026 +0 days VulDB entry created 04/11/2026 +0 days VulDB entry last update Sourcesinfo Advisory: wordfence.com Researcher: Quốc Huy Status: Not defined CVE: CVE-2026-5217 (🔒) GCVE (CVE): GCVE-0-2026-5217 GCVE (VulDB): GCVE-100-356952 EUVD: 🔒 Entryinfo Created: 04/11/2026 04:10 Updated: 04/11/2026 10:04 Changes: 04/11/2026 04:10 (66), 04/11/2026 10:04 (1) Complete: 🔍 Cache ID: 99:465:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸