CWE · MITRE source
CWE-551Incorrect Behavior Order: Authorization Before Parsing and Canonicalization
If a web server does not fully parse requested URLs before it examines them for authorization, it may be possible for an attacker to bypass authorization protection.
For instance, the character strings /./ and / both mean current directory. If /SomeDirectory is a protected directory and an attacker requests /./SomeDirectory, the attacker may be able to gain access to the resource if /./ is not converted to / before the authorization check is performed.
Last updated: 14 October 2026 20:41 UTC
Control responseHuman-reviewed
Answering this weakness across the control lifecycle, from our framework cross-walks.
NIST 800-53 r5 controls PROPOSED for this weakness (0)AI-assisted
These are model PROPOSALS, not graded mappings. They come
from controls_to_cwe_proposals, which carries no grade field at
all; across the CWE pages 1,540 of 1,722 such associations (89%) have never
been graded by anything. The heading said “address” until
2026-09-29, which asserted a relationship the data does not carry.
Graded cross-walks are on the framework map, not here.
| Control | Title | Family | Why it addresses this CWE |
|---|---|---|---|
| No NIST controls proposed yet. | |||
Top CVEs of this weakness type, ranked by Risk Priority
| CVE | Risk | CVSS | EPSS | Published |
|---|---|---|---|---|
CVE-2021-28165 UPD | 8.0 | 7.5 | 0.5386 | 2021-04-01 |
CVE-2023-23924 UPD | 7.9 | 10.0 | 0.0357 | 2023-02-01 |
CVE-2026-2293 UPD | 7.4 | 9.8 | 0.0068 | 2026-02-27 |
CVE-2016-20030 UPD | 7.4 | 9.8 | 0.0057 | 2026-03-16 |
CVE-2026-28808 UPD | 7.4 | 9.8 | 0.0077 | 2026-04-07 |
CVE-2026-33186 UPD | 7.2 | 9.1 | 0.0163 | 2026-03-20 |
CVE-2021-34429 UPD | 7.1 | 5.3 | 0.9930 | 2021-07-15 |
CVE-2021-28164 UPD | 7.0 | 5.3 | 0.8237 | 2021-04-01 |
CVE-2021-32777 UPD | 6.7 | 8.6 | 0.0333 | 2021-08-24 |
CVE-2026-45832 UPD | 6.6 | 8.8 | 0.0052 | 2026-06-12 |
CVE-2021-32779 UPD | 6.4 | 8.6 | 0.0095 | 2021-08-24 |
CVE-2026-40022 UPD | 6.4 | 8.2 | 0.0103 | 2026-04-27 |
CVE-2026-39852 UPD | 6.3 | 8.2 | 0.0063 | 2026-05-05 |
CVE-2026-44574 UPD | 6.2 | 8.1 | 0.0067 | 2026-05-13 |
CVE-2026-4636 UPD | 6.1 | 8.1 | 0.0048 | 2026-04-02 |
CVE-2026-15573 UPD | 6.1 | 8.1 | 0.0046 | 2026-08-05 |
CVE-2026-16102 UPD | 6.1 | 8.1 | 0.0046 | 2026-08-05 |
CVE-2026-44573 UPD | 6.0 | 7.5 | 0.0076 | 2026-05-13 |
CVE-2026-44575 UPD | 6.0 | 7.5 | 0.0076 | 2026-05-13 |
CVE-2026-50559 UPD | 6.0 | 7.5 | 0.0102 | 2026-06-19 |
CVE-2026-13676 UPD | 5.9 | 7.5 | 0.0048 | 2026-06-29 |
CVE-2026-87743 | 5.9 | 7.5 | 0.0052 | 2026-09-18 |
CVE-2026-22754 UPD | 5.7 | 7.5 | 0.0027 | 2026-04-22 |
CVE-2026-89060 UPD | 5.7 | 7.7 | 0.0047 | 2026-09-11 |
CVE-2021-31384 UPD | 5.6 | 7.2 | 0.0116 | 2021-10-19 |