CWE · MITRE source
CWE-86Improper Neutralization of Invalid Characters in Identifiers in Web Pages
The product does not neutralize or incorrectly neutralizes invalid characters or byte sequences in the middle of tag names, URI schemes, and other identifiers.
Some web browsers may remove these sequences, resulting in output that may have unintended control implications. For example, the product may attempt to remove a "javascript:" URI scheme, but a "java%00script:" URI may bypass this check and still be rendered as active javascript by some browsers, allowing XSS or other attacks.
Last updated: 04 July 2026 08:17 UTC
Cumulative inbound coverage
How completely the frameworks we cross-walk collectively cover this — the verdict is the strongest single mapping (overlapping partials are not summed); breadth shows the corroboration behind it.
Collective: partial · 5 mapping(s) from 3 framework(s): CAPEC 2 (partial) · ATT&CK 2 (partial) · OWASP-Web 1 (partial)
OWASP Top 10 for Web (2025)
This weakness contributes to A05:2025 Injection.
NIST 800-53 r5 controls that address this weakness (0)AI
| Control | Title | Family | Why it addresses this CWE |
|---|---|---|---|
| No NIST controls proposed yet. | |||
MITRE ATT&CK techniques this weakness enables
Our own two-way CWE↔ATT&CK cross-walk — a direct mapping with no public source (the CWE→CAPEC→ATT&CK chain leaves most top weaknesses, incl. XSS and SQLi, mapped to nothing). Drafted by Grok and spot-checked by Claude Opus 4.8.
Direction: ← other covers this;
→ this covers other (F/M/P = full / mostly /
partial).
Top CVEs of this weakness type, ranked by Risk Priority
| CVE | Risk | CVSS | EPSS | Published |
|---|---|---|---|---|
CVE-2023-31126 | 7.0 | 9.0 | 0.0082 | 2023-05-09 |
CVE-2025-66606 | 7.0 | 9.6 | 0.0022 | 2026-02-09 |
CVE-2021-33158 | 5.5 | 7.2 | 0.0021 | 2024-02-23 |
CVE-2024-21864 | 5.5 | 7.8 | 0.0034 | 2024-05-16 |
CVE-2024-10941 | 3.5 | 6.5 | 0.0039 | 2024-11-06 |
CVE-2025-20166 | 3.5 | 5.4 | 0.0036 | 2025-01-08 |
CVE-2025-20167 | 3.5 | 5.4 | 0.0028 | 2025-01-08 |
CVE-2025-20168 | 3.5 | 5.4 | 0.0028 | 2025-01-08 |
CVE-2026-28417 | 3.5 | 4.4 | 0.0116 | 2026-02-27 |
CVE-2023-22840 | 1.5 | 3.3 | 0.0044 | 2023-08-11 |