CWE-185
Incorrect Regular Expression
The product specifies a regular expression in a way that causes data to be improperly matched or compared.
CVE-2026-3419 (GCVE-0-2026-3419)
Vulnerability from cvelistv5 – Published: 2026-03-06 17:50 – Updated: 2026-03-09 14:55
VLAI
Title
Fastify's Missing End Anchor in "subtypeNameReg" Allows Malformed Content-Types to Pass Validation
Summary
Fastify incorrectly accepts malformed `Content-Type` headers containing trailing characters after the subtype token, in violation of RFC 9110 §8.3.1(https://httpwg.org/specs/rfc9110.html#field.content-type). For example, a request sent with Content-Type: application/json garbage passes validation and is processed normally, rather than being rejected with 415 Unsupported Media Type.
When regex-based content-type parsers are in use (a documented Fastify feature), the malformed value is matched against registered parsers using the full string including the trailing garbage. This means a request with an invalid content-type may be routed to and processed by a parser it should never have reached.
Impact:
An attacker can send requests with RFC-invalid Content-Type headers that bypass validity checks, reach content-type parser matching, and be processed by the server. Requests that should be rejected at the validation stage are instead handled as if the content-type were valid.
Workarounds:
Deploy a WAF rule to protect against this
Fix:
The fix is available starting with v5.8.1.
Severity
5.3 (Medium)
CWE
- CWE-185 - Incorrect Regular Expression
Assigner
References
6 references
Impacted products
Credits
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CVE-2026-39350 (GCVE-0-2026-39350)
Vulnerability from cvelistv5 – Published: 2026-04-15 22:42 – Updated: 2026-04-16 12:04
VLAI
Title
Istio AuthorizationPolicy Incorrect Regex Matching of Dots in serviceAccounts Fields Allows Policy Bypass
Summary
Istio is an open platform to connect, manage, and secure microservices. In versions 1.25.0 through 1.27.8, 1.28.0 through 1.28.5, 1.29.0, and 1.29.1, the serviceAccounts and notServiceAccounts fields in AuthorizationPolicy incorrectly interpret dots (.) as a regular expression matcher. Because . is a valid character in a service account name, an AuthorizationPolicy ALLOW rule targeting a service account such as cert-manager.io also matches cert-manager-io, cert-managerXio, etc. A DENY rule targeting the same name fails to block those variants. Fixes are available in versions 1.29.2, 1.28.6, and 1.27.9.
Severity
5.4 (Medium)
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/istio/istio/security/advisorie… | x_refsource_CONFIRM |
Impacted products
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CVE-2026-4296 (GCVE-0-2026-4296)
Vulnerability from cvelistv5 – Published: 2026-04-21 22:12 – Updated: 2026-04-22 13:16
VLAI
Title
Incorrect Regular Expression vulnerability in GitHub Enterprise Server allowed unauthorized access to user accounts via OAuth callback URL validation bypass
Summary
An incorrect regular expression vulnerability was identified in GitHub Enterprise Server that allowed an attacker to bypass OAuth redirect URI validation. An attacker with knowledge of a first-party OAuth application's registered callback URL could craft a malicious authorization link that, when clicked by a victim, would redirect the OAuth authorization code to an attacker-controlled domain. This could allow the attacker to gain unauthorized access to the victim's account with the scopes granted to the OAuth application. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.20.1, 3.19.5, 3.18.8, 3.17.14, 3.16.17, 3.15.21, 3.14.26. This vulnerability was reported via the GitHub Bug Bounty program.
Severity
CWE
- CWE-185 - Incorrect Regular Expression
Assigner
References
7 references
| URL | Tags |
|---|---|
| https://docs.github.com/en/enterprise-server@3.14… | release-notes |
| https://docs.github.com/en/enterprise-server@3.15… | release-notes |
| https://docs.github.com/en/enterprise-server@3.16… | release-notes |
| https://docs.github.com/en/enterprise-server@3.17… | release-notes |
| https://docs.github.com/en/enterprise-server@3.18… | release-notes |
| https://docs.github.com/en/enterprise-server@3.19… | release-notes |
| https://docs.github.com/en/enterprise-server@3.20… | release-notes |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| GitHub | Enterprise Server |
Affected:
3.14.0 , ≤ 3.14.25
(semver)
Affected: 3.15.0 , ≤ 3.15.20 (semver) Affected: 3.16.0 , ≤ 3.16.16 (semver) Affected: 3.17.0 , ≤ 3.17.13 (semver) Affected: 3.18.0 , ≤ 3.18.7 (semver) Affected: 3.19.0 , ≤ 3.19.4 (semver) Affected: 3.20.0 , < 3.20.1 (semver) |
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Mitigation ID: MIT-45
Phase: Implementation
Strategy: Refactoring
Description:
- 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 the 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 the regular expression.
CAPEC-15: Command Delimiters
An attack of this type exploits a programs' vulnerabilities that allows an attacker's commands to be concatenated onto a legitimate command with the intent of targeting other resources such as the file system or database. The system that uses a filter or denylist input validation, as opposed to allowlist validation is vulnerable to an attacker who predicts delimiters (or combinations of delimiters) not present in the filter or denylist. As with other injection attacks, the attacker uses the command delimiter payload as an entry point to tunnel through the application and activate additional attacks through SQL queries, shell commands, network scanning, and so on.
CAPEC-6: Argument Injection
An attacker changes the behavior or state of a targeted application through injecting data or command syntax through the targets use of non-validated and non-filtered arguments of exposed services or methods.
CAPEC-79: Using Slashes in Alternate Encoding
This attack targets the encoding of the Slash characters. An adversary would try to exploit common filtering problems related to the use of the slashes characters to gain access to resources on the target host. Directory-driven systems, such as file systems and databases, typically use the slash character to indicate traversal between directories or other container components. For murky historical reasons, PCs (and, as a result, Microsoft OSs) choose to use a backslash, whereas the UNIX world typically makes use of the forward slash. The schizophrenic result is that many MS-based systems are required to understand both forms of the slash. This gives the adversary many opportunities to discover and abuse a number of common filtering problems. The goal of this pattern is to discover server software that only applies filters to one version, but not the other.