VulnerabilityPublished 3 Nov 2025

CVE-2024-6866: corydolphin/flask-cors · Improper Handling of Case Sensitivity

Affects corydolphin/flask-corsSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.0 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.7% chance of exploitation in 30 days – higher than 53% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N

Attack Vector: Network
Attack Complexity: High
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 3 Nov 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
GitHubcorydolphin/flask-cors`pkg:github/corydolphin/flask-cors`Other threats	Affected =4.01	Fixed in–

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AI-suggested

Upgrade to a patched version of corydolphin/flask-cors once available that correctly handles case sensitivity in path matching.
In the interim, implement custom CORS middleware or logic that enforces strict, case-sensitive path matching to prevent unauthorized origin access.
Review and audit all CORS configurations in web applications to ensure that path-based restrictions are correctly applied and tested for case sensitivity.
Employ web application firewalls (WAFs) with rules to detect and block suspicious cross-origin requests that do not comply with expected path cases.
Conduct penetration testing focused on CORS misconfigurations and path case sensitivity to identify potential exploit vectors.
Educate developers and security teams on the importance of case sensitivity in URL handling and CORS policies.
Monitor logs for unusual cross-origin requests that could indicate exploitation attempts.
For critical applications, consider implementing additional authentication or authorization checks beyond CORS to protect sensitive endpoints.

Description

corydolphin/flask-cors version 5.0.1 contains a vulnerability where the request path matching is case-insensitive due to the use of the `try_match` function, which is originally intended for matching hosts. This results in a mismatch because paths in URLs are case-sensitive, but the regex matching treats them as case-insensitive. This misconfiguration can lead to significant security vulnerabilities, allowing unauthorized origins to access paths meant to be restricted, resulting in data exposure and potential data leaks.

Impact

For European organizations, this vulnerability poses a risk of unauthorized data exposure through misconfigured CORS policies in web applications using the affected flask-cors library. Sensitive internal APIs or resources intended to be restricted by path-based CORS rules could be accessed by malicious origins, leading to potential data leaks or privacy violations. This is particularly concerning for sectors handling personal data under GDPR, such as finance, healthcare, and government services. The impact is primarily on confidentiality, with no direct effect on system integrity or availability. Exploitation requires network access and user interaction, which may limit automated attacks but still allows targeted phishing or social engineering campaigns to trigger the vulnerability. Organizations relying on flask-cors in microservices or cloud-native architectures may face increased exposure due to the widespread use of CORS for cross-domain requests. Failure to address this vulnerability could result in regulatory penalties and reputational damage if data breaches occur.

Summary

CVE-2024-6866 affects the corydolphin/flask-cors library, specifically version 4.01, due to improper handling of case sensitivity in URL path matching. The vulnerability stems from the use of the `try_match` function, which was originally intended for matching hostnames in a case-insensitive manner, being incorrectly applied to URL paths. Since URL paths are case-sensitive by standard, this misapplication causes the matching logic to treat paths as case-insensitive, allowing requests from unauthorized origins to access resources that should be restricted. This can lead to unauthorized cross-origin resource sharing (CORS) access, potentially exposing sensitive data or internal endpoints to malicious actors. The vulnerability is classified under CWE-178 (Improper Handling of Case Sensitivity). The CVSS 3.0 base score is 5.3, reflecting a medium severity with network attack vector, high attack complexity, no privileges required, and requiring user interaction. There are no known exploits in the wild at the time of publication. The flaw primarily impacts confidentiality, as unauthorized origins may gain access to sensitive data, but does not affect integrity or availability. The vulnerability is particularly relevant for web applications relying on flask-cors for CORS policy enforcement, especially those that depend on path-based restrictions to control resource access. Without proper patching or configuration adjustments, attackers could exploit this to bypass security controls.

CWE-178Improper Handling of Case Sensitivity (opens in a new tab)
Base weakness
The product does not properly account for differences in case sensitivity when accessing or determining the properties of a resource, leading to inconsistent results.
Architecture and Design · Input Validation
Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Implementation · Input Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174).
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 3 Nov 2025, 20:07 UTC

WeaknessesCWE-178

Technical details

References

Community reviews

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