CVE-2026-89253
CRITICAL 9.3 PoC AVAILABLE ALL-YEARSWWBN AVideo through commit c3edcc274c389816d434acadac07ee78eaf330c1 contains a stored cross-site scripting vulnerability in the user 'donationLink' profile field. User::setDonationLink() (objects/user.php) stores the value and save() validates it only with filter_var(..., FILTER_VALIDATE_URL), which accepts strings such as http://evil.example/"onmouseover=alert(document.domain)//, while getDonationLink() applies only strip_tags() and does not encode double quotes. plugin/CustomizeUser/actionButton.php echoes the value unencoded into an <a href="..."> attribute, and that button is included from view/modeYoutubeBottom.php on the watch page when the CustomizeUser option allowDonationLink is enabled. An authenticated user who updates their own profile via objects/userUpdate.json.php can therefore break out of the href attribute and inject an event handler that executes JavaScript in the browser of any visitor—including an administrator—who views the attacker's videos and interacts with (for example, hovers over) the donation button. The issue was unfixed at the time of reporting.
Public exploit or PoC code exists. The barrier to attack is reduced — watch closely.
Exploitation likelihood
0.4%chance of exploitation in 30 days · 29th percentile
Impact if exploited
9.3CVSS 4.0 · CRITICAL · CNA
- ConfidentialityHigh
- IntegrityHigh
- AvailabilityNone
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ⚠Privileges: Requires a low-privilege account
- ⚠User interaction: Succeeds with passive user activity
- ✓Complexity: No special conditions — reliably repeatable
- ✓Requirements: No special attack requirements
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept & exploit code
- reference https://github.com/WWBN/AVideo/security/advisories/GHSA-34jx-r3p9-7pp2
- github-search https://github.com/search?q=%22CVE-2026-89253%22&type=repositories
Test against your own equipment
curl -s https://vulnpedia.com/cve/CVE-2026-89253/poc.jsonMachine-readable PoC index for this CVE (for automation).For defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-89253/poc.json
Weakness (CWE)
- CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N
All CVSS metrics
- CRITICAL 9.3 v4.0 · CNA Primary
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N - HIGH 8.7 v3.1 · CNA Primary
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N - CRITICAL 9.3 v4.0 · NVD Secondary
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/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 - HIGH 8.7 v3.1 · NVD Secondary
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N