CWE-1333
Inefficient Regular Expression Complexity
The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.
CVE-2026-4867 (GCVE-0-2026-4867)
Vulnerability from cvelistv5 – Published: 2026-03-26 16:16 – Updated: 2026-03-26 16:52
VLAI
Title
path-to-regexp vulnerable to Regular Expression Denial of Service via multiple route parameters
Summary
Impact:
A bad regular expression is generated any time you have three or more parameters within a single segment, separated by something that is not a period (.). For example, /:a-:b-:c or /:a-:b-:c-:d. The backtrack protection added in path-to-regexp@0.1.12 only prevents ambiguity for two parameters. With three or more, the generated lookahead does not block single separator characters, so capture groups overlap and cause catastrophic backtracking.
Patches:
Upgrade to path-to-regexp@0.1.13
Custom regex patterns in route definitions (e.g., /:a-:b([^-/]+)-:c([^-/]+)) are not affected because they override the default capture group.
Workarounds:
All versions can be patched by providing a custom regular expression for parameters after the first in a single segment. As long as the custom regular expression does not match the text before the parameter, you will be safe. For example, change /:a-:b-:c to /:a-:b([^-/]+)-:c([^-/]+).
If paths cannot be rewritten and versions cannot be upgraded, another alternative is to limit the URL length.
Severity
7.5 (High)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-1333 - Inefficient Regular Expression Complexity
Assigner
References
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| path-to-regexp | path-to-regexp |
Affected:
0 , < 0.1.13
(semver)
|
Credits
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CVE-2026-4923 (GCVE-0-2026-4923)
Vulnerability from cvelistv5 – Published: 2026-03-26 19:02 – Updated: 2026-03-27 13:58
VLAI
Title
path-to-regexp vulnerable to Regular Expression Denial of Service via multiple wildcards
Summary
Impact:
When using multiple wildcards, combined with at least one parameter, a regular expression can be generated that is vulnerable to ReDoS. This backtracking vulnerability requires the second wildcard to be somewhere other than the end of the path.
Unsafe examples:
/*foo-*bar-:baz
/*a-:b-*c-:d
/x/*a-:b/*c/y
Safe examples:
/*foo-:bar
/*foo-:bar-*baz
Patches:
Upgrade to version 8.4.0.
Workarounds:
If you are using multiple wildcard parameters, you can check the regex output with a tool such as https://makenowjust-labs.github.io/recheck/playground/ to confirm whether a path is vulnerable.
Severity
5.9 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-1333 - Inefficient Regular Expression Complexity
Assigner
References
1 reference
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
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Affected:
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(semver)
Unaffected: 8.4.0 (semver) |
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CVE-2026-4926 (GCVE-0-2026-4926)
Vulnerability from cvelistv5 – Published: 2026-03-26 18:59 – Updated: 2026-03-27 19:44
VLAI
Title
path-to-regexp vulnerable to Denial of Service via sequential optional groups
Summary
Impact:
A bad regular expression is generated any time you have multiple sequential optional groups (curly brace syntax), such as `{a}{b}{c}:z`. The generated regex grows exponentially with the number of groups, causing denial of service.
Patches:
Fixed in version 8.4.0.
Workarounds:
Limit the number of sequential optional groups in route patterns. Avoid passing user-controlled input as route patterns.
Severity
7.5 (High)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
Assigner
References
1 reference
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| path-to-regexp | path-to-regexp |
Affected:
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CVE-2026-5986 (GCVE-0-2026-5986)
Vulnerability from cvelistv5 – Published: 2026-04-09 22:30 – Updated: 2026-04-14 03:12
VLAI
Title
Zod jsVideoUrlParser util.js getTime redos
Summary
A weakness has been identified in Zod jsVideoUrlParser up to 0.5.1. The impacted element is the function getTime in the library lib/util.js. This manipulation of the argument timestamp causes inefficient regular expression complexity. It is possible to initiate the attack remotely. The exploit has been made available to the public and could be used for attacks. The project was informed of the problem early through an issue report but has not responded yet.
Severity
SSVC
Exploitation: poc
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
Assigner
References
5 references
| URL | Tags |
|---|---|
| https://vuldb.com/vuln/356540 | vdb-entrytechnical-description |
| https://vuldb.com/vuln/356540/cti | signaturepermissions-required |
| https://vuldb.com/submit/791911 | third-party-advisory |
| https://github.com/Zod-/jsVideoUrlParser/issues/121 | issue-tracking |
| https://github.com/Zod-/jsVideoUrlParser/issues/1… | exploitissue-tracking |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Zod | jsVideoUrlParser |
Affected:
0.5.0
Affected: 0.5.1 |
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CVE-2026-8159 (GCVE-0-2026-8159)
Vulnerability from cvelistv5 – Published: 2026-05-12 08:35 – Updated: 2026-05-12 12:33
VLAI
Title
multiparty vulnerable to ReDoS via filename parsing
Summary
multiparty@4.2.3 and lower versions are vulnerable to denial of service via regular expression backtracking in the Content-Disposition filename parameter parser. A crafted multipart upload with a long header value can cause regex matching to take seconds, blocking the event loop. Impact: any service accepting multipart uploads via multiparty is affected. Workarounds: limiting upload sizes at the proxy or gateway layer reduces but does not eliminate the attack surface, since a small header of around 8 KB is sufficient to trigger the vulnerable backtracking. Upgrade to multiparty@4.3.0 or higher.
Severity
7.5 (High)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-1333 - Inefficient Regular Expression Complexity
Assigner
References
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| multiparty | multiparty |
Affected:
0 , ≤ 4.2.3
(semver)
Unaffected: 4.3.0 (semver) |
Credits
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Mitigation
Phase: Architecture and Design
Description:
- Use regular expressions that do not support backtracking, e.g. by removing nested quantifiers.
Mitigation
Phase: System Configuration
Description:
- Set backtracking limits in the configuration of the regular expression implementation, such as PHP's pcre.backtrack_limit. Also consider limits on execution time for the process.
Mitigation
Phase: Implementation
Description:
- Do not use regular expressions with untrusted input. If regular expressions must be used, avoid using backtracking in the expression.
Mitigation
Phase: Implementation
Description:
- Limit the length of the input that the regular expression will process.
CAPEC-492: Regular Expression Exponential Blowup
An adversary may execute an attack on a program that uses a poor Regular Expression(Regex) implementation by choosing input that results in an extreme situation for the Regex. A typical extreme situation operates at exponential time compared to the input size. This is due to most implementations using a Nondeterministic Finite Automaton(NFA) state machine to be built by the Regex algorithm since NFA allows backtracking and thus more complex regular expressions.