The product uses a regular expression that does not sufficiently restrict the set of allowed values.
This effectively causes the regexp to accept substrings that match the pattern, which produces a partial comparison to the target. In some cases, this can lead to other weaknesses. Common errors include:
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| ChildOf | Allowed-with-Review | C | 185 | Incorrect Regular Expression |
| ParentOf | Allowed | V | 777 | Regular Expression without Anchors |
| PeerOf | Allowed | V | 187 | Partial String Comparison |
| PeerOf | Allowed | B | 184 | Incomplete List of Disallowed Inputs |
| PeerOf | Allowed | B | 183 | Permissive List of Allowed Inputs |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | C | 19 | Data Processing Errors |
| MemberOf | Prohibited | C | 845 | The CERT Oracle Secure Coding Standard for Java (2011) Chapter 2 - Input Validation and Data Sanitization (IDS) |
| MemberOf | Prohibited | C | 990 | SFP Secondary Cluster: Tainted Input to Command |
| MemberOf | Prohibited | C | 1397 | Comprehensive Categorization: Comparison |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | BS | BOSS-250 | Weaknesses in Software Written in Perl |
| MemberOf | Prohibited | BS | BOSS-316 | Bypass Protection Mechanism (impact) |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | C | 19 | Data Processing Errors |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | C | 990 | SFP Secondary Cluster: Tainted Input to Command |
| Scope | Likelihood | Impact | Note |
|---|---|---|---|
| Access Control | N/A | Bypass Protection Mechanism | N/A |
When applicable, ensure that the regular expression marks beginning and ending string patterns, such as "/^string$/" for Perl.
This problem is frequently found when the regular expression is used in input validation or security features such as authentication.
The following code takes phone numbers as input, and uses a regular expression to reject invalid phone numbers.
An attacker could provide an argument such as: "; ls -l ; echo 123-456" This would pass the check, since "123-456" is sufficient to match the "\d+-\d+" portion of the regular expression.
This code uses a regular expression to validate an IP string prior to using it in a call to the "ping" command.
Since the regular expression does not have anchors (CWE-777), i.e. is unbounded without ^ or $ characters, then prepending a 0 or 0x to the beginning of the IP address will still result in a matched regex pattern. Since the ping command supports octal and hex prepended IP addresses, it will use the unexpectedly valid IP address (CWE-1389). For example, "0x63.63.63.63" would be considered equivalent to "99.63.63.63". As a result, the attacker could potentially ping systems that the attacker cannot reach directly.
| Reference | Description |
|---|---|
| CVE-2021-22204 | Chain: regex in EXIF processor code does not correctly determine where a string ends (CWE-625), enabling eval injection (CWE-95), as exploited in the wild per CISA KEV. |
| CVE-2006-1895 | ".*" regexp leads to static code injection |
| CVE-2002-2175 | insertion of username into regexp results in partial comparison, causing wrong database entry to be updated when one username is a substring of another. |
| CVE-2006-4527 | regexp intended to verify that all characters are legal, only checks that at least one is legal, enabling file inclusion. |
| CVE-2005-1949 | Regexp for IP address isn't anchored at the end, allowing appending of shell metacharacters. |
| CVE-2002-2109 | Regexp isn't "anchored" to the beginning or end, which allows spoofed values that have trusted values as substrings. |
| CVE-2006-6511 | regexp in .htaccess file allows access of files whose names contain certain substrings |
| CVE-2006-6629 | allow load of macro files whose names contain certain substrings. |
| Ordinality | Description |
|---|---|
| Primary | N/A |
Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
N/A
This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
| Taxonomy Name | Entry ID | Fit | Entry Name |
|---|---|---|---|
| The CERT Oracle Secure Coding Standard for Java (2011) | IDS08-J | N/A | Sanitize untrusted data passed to a regex |
| ID | Name |
|---|