Common Weakness Enumeration
CWE-186
AllowedOverly Restrictive Regular Expression
Abstraction: Base · Status: Draft
A regular expression is overly restrictive, which prevents dangerous values from being detected.
3 vulnerabilities reference this CWE, most recent first.
CVE-2026-121373 (GCVE-0-2026-121373)
Vulnerability from cvelistv5 – Published: 2026-11-04 12:59 – Updated: 2026-11-04 18:20
VLAI
EPSS
VEX
Title
Symfony: HtmlSanitizer MetaRefreshAttributeSanitizer Matches Only a Narrow Subset of the Browser Refresh Grammar (Incomplete Fix for CVE-2026-48761)
Summary
The Symfony HtmlSanitizer component MetaRefreshAttributeSanitizer, introduced to fix CVE-2026-48761, sanitizes the refresh URL of content attributes of meta tags using a regular expression that is too narrow, allowing sanitization to be bypassed, and resulting in potential URL redirection to untrusted sites in Symfony versions 6.1.x prior to 6.4.50, 7.x prior to 7.4.23, and 8.x prior to 8.1.11.
The shared declarative refresh steps in the WHATWG HTML Standard require a broader approach: the separator after the time may be ASCII whitespace alone, with no ; or ,, and the url= keyword is optional. Directives the browser honours, but the regular expression misses are returned unchanged, so the attacker URL skips UrlSanitizer entirely and both allowLinkSchemes and allowLinkHosts are defeated for the refresh navigation.
This is reachable under any configuration that allows meta with http-equiv and content, including the documented allowStaticElements() preset.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-11-04 17:49 UTC
CWE
Assigner
Checkmarx
CNA
References
2 references
| URL | Tags |
|---|---|
| https://github.com/symfony/symfony/security/advis… | third-party-advisory |
| https://github.com/symfony/symfony/commit/2d4c4fe… | patch |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| sensiolabs | symfony |
Affected:
6.1.0 , < 6.4.50
(git)
Affected: 7.0.0 , < 7.4.23 (git) Affected: 8.0.0 , < 8.1.11 (git) cpe:2.3:a:sensiolabs:symfony:*:*:*:*:*:*:*:* cpe:2.3:a:sensiolabs:symfony:*:*:*:*:*:*:*:* cpe:2.3:a:sensiolabs:symfony:*:*:*:*:*:*:*:* |
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CVE-2026-47241 (GCVE-0-2026-47241)
Vulnerability from cvelistv5 – Published: 2026-06-22 20:11 – Updated: 2026-06-23 14:16
VLAI
EPSS
VEX
Title
Net::IMAP: Denial of Service via incomplete raw argument validation
Summary
Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to 0.6.5 and 0.5.15, several Net::IMAP commands accept a raw string argument which is only validated to prevent CRLF injection and then sent verbatim. If this string is derived from user-controlled input, an attacker can force the next command to be absorbed as a continuation of the first command. This will cause the first command to eventually fail, but also prevents it from returning until another command is sent (from another thread). That other command will not return until the connection is closed. This vulnerability is fixed in 0.6.5 and 0.5.15.
Severity
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-06-23 14:16 UTC
CWE
Assigner
GitHub_M
CNA
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/ruby/net-imap/security/advisor… | x_refsource_CONFIRM |
Impacted products
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CVE-2025-46821 (GCVE-0-2025-46821)
Vulnerability from cvelistv5 – Published: 2025-05-07 21:24 – Updated: 2025-05-08 14:11
VLAI
EPSS
VEX
Title
Envoy vulnerable to bypass of RBAC uri_template permission
Summary
Envoy is a cloud-native edge/middle/service proxy. Prior to versions 1.34.1, 1.33.3, 1.32.6, and 1.31.8, Envoy's URI template matcher incorrectly excludes the `*` character from a set of valid characters in the URI path. As a result URI path containing the `*` character will not match a URI template expressions. This can result in bypass of RBAC rules when configured using the `uri_template` permissions. This vulnerability is fixed in Envoy versions v1.34.1, v1.33.3, v1.32.6, v1.31.8. As a workaround, configure additional RBAC permissions using `url_path` with `safe_regex` expression.
Severity
5.3 (Medium)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-05-08 13:43 UTC
CWE
- CWE-186 - Overly Restrictive Regular Expression
Assigner
GitHub_M
CNA
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/envoyproxy/envoy/security/advi… | x_refsource_CONFIRM |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| envoyproxy | envoy |
Affected:
< 1.31.8
Affected: >= 1.32.0, < 1.32.6 Affected: >= 1.33.0, < 1.33.3 Affected: >= 1.34.0, < 1.34.1 |
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Mitigation MIT-45
Implementation
Strategy: Refactoring
Regular expressions can become error prone when defining a complex language even for those experienced in writing grammars. Determine if several smaller regular expressions simplify one large regular expression. Also, subject your regular expression to thorough testing techniques such as equivalence partitioning, boundary value analysis, and robustness. After testing and a reasonable confidence level is achieved, a regular expression may not be foolproof. If an exploit is allowed to slip through, then record the exploit and refactor your regular expression.
No CAPEC attack patterns related to this CWE.