VulnerabilityPublished 3 Nov 2025

CVE-2024-6839: corydolphin/flask-cors · Improper Resolution of Path Equivalence

Affects corydolphin/flask-corsSource CVE Database V5

Not known to be exploited · CVSS 4.3 Medium.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.0 base score

4.3Medium

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

EPSS: 0.7% chance of exploitation in 30 days – higher than 54% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: Low
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: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
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: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
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 =4.0.1	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

To mitigate CVE-2024-6839, European organizations should: 1) Immediately audit all flask-cors configurations focusing on regex path patterns to ensure that more specific patterns are prioritized correctly and no overly permissive patterns exist. 2) Where possible, replace regex-based path matching with explicit allowlists or exact path matching to avoid ambiguity. 3) Monitor cross-origin requests and CORS headers in production environments to detect anomalous or unauthorized access attempts. 4) Stay alert for official patches or updates from the corydolphin/flask-cors project and apply them promptly once available. 5) Educate developers on secure CORS configuration best practices, emphasizing the risks of improper regex prioritization. 6) Consider implementing additional application-layer access controls to sensitive endpoints beyond CORS policies. 7) Use web application firewalls (WAFs) to block suspicious cross-origin requests if feasible. These steps go beyond generic advice by focusing on regex pattern auditing and layered security controls specific to this vulnerability.

Description

corydolphin/flask-cors version 4.0.1 contains an improper regex path matching vulnerability. The plugin prioritizes longer regex patterns over more specific ones when matching paths, which can lead to less restrictive CORS policies being applied to sensitive endpoints. This mismatch in regex pattern priority allows unauthorized cross-origin access to sensitive data or functionality, potentially exposing confidential information and increasing the risk of unauthorized actions by malicious actors.

Impact

For European organizations, this vulnerability can lead to unauthorized cross-origin access to sensitive web application endpoints, potentially exposing confidential user data or internal functionality. This exposure increases the risk of data breaches, privacy violations under GDPR, and unauthorized operations that could disrupt business processes or compromise user trust. Since flask-cors is commonly used in Python-based web applications, organizations relying on this library for CORS management are at risk if they use vulnerable versions and have complex regex patterns for path matching. The impact is particularly significant for sectors handling sensitive personal or financial data, such as finance, healthcare, and government services. Although the vulnerability does not directly affect system integrity or availability, the confidentiality breach and potential for unauthorized actions pose compliance and reputational risks. The medium severity rating suggests that while exploitation is feasible, the overall damage is limited to confidentiality and requires user interaction.

CWE-41Improper Resolution of Path Equivalence (opens in a new tab)
Base weakness
The product is vulnerable to file system contents disclosure through path equivalence. Path equivalence involves the use of special characters in file and directory names. The associated manipulations are intended to generate multiple names for the same object.
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 · Output Encoding
Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8.
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).
OWASP ASVS 4.0.3
V8.3.8 (opens in a new tab)
V2.8.5 (opens in a new tab)
V2.8.4 (opens in a new tab)
Attack patterns
Using Leading 'Ghost' Character Sequences to Bypass Input Filters (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

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

WeaknessesCWE-41

Technical details

References

Community reviews

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