wp_kses_bad_protocol in wp-includes/kses.php in WordPress before 5.3.1 mishandles the HTML5 colon named entity, allowing attackers to bypass input sanitization, as demonstrated by the javascript: substring.
An official patch is available. Apply the patch as soon as possible.
CVSS v4.0 Metrics
Exploitability
Attack VectorNetwork
ComplexityLow
RequirementsPresent
PrivilegesNone
User InteractionNone
Threat
Exploit MaturityPoC
Vulnerable System
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
Subsequent System
ConfidentialityNone
IntegrityNone
AvailabilityNone
Supplemental
SafetyNegligible
AutomatableYes
RecoveryAutomatic
Value DensityConcentrated
UrgencyMedium
Patch StatusOfficial Patch
Change Log
| Date | Source | Changes | Score |
|---|
| 2026-07-21 | PoC | E: U→P | 7.2 → 8.2 |
| 2026-07-21 | nvd | AV: P→N, AC: H→L, PR: H→N, UI: A→N, VC: N→H, VI: N→H, VA: N→H | 0.0 → 7.2 |
| 2026-07-21 | nvd | patch: Unavailable→Official Patch | 0.0 → 0.0 |
| 2026-07-21 | cve.org | initial, patch: Unavailable | 0.0 |
Affected Software
| Vendor | Product | Version |
|---|
| debian | debian_linux | 10.0 |
| debian | debian_linux | 8.0 |
| debian | debian_linux | 9.0 |
| wordpress | wordpress | < 5.3.1 |
Published: 2019-12-27
