VulnerabilityPublished 16 Sep 2026

CVE-2026-14916: Kong Enteprise Gateway · Improper Handling of Unexpected Data Type

Affects Kong Enteprise GatewaySource CVE Database V5

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Not known to be exploited · CVSS 7.7 High · fixed in 3.15.0.3 : patch Kong Enteprise Gateway soon.

Data as of 30 Oct 2026, 20:25 UTC

CVSS 4.0 base score

7.7High

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

EPSS: 0.6% chance of exploitation in 30 days – higher than 53% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.15.0.3, 3.14.0.12, 3.13.0.9 +3

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: None
Subsequent system confidentiality: High
Subsequent system integrity: None
Subsequent system availability: None

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

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, 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: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: High: There is a total loss of confidentiality, resulting in all resources within the Subsequent System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 16 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 30 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
KongKong Enteprise Gateway	Affected >=3.15.0.0 <3.15.0.3	Fixed in 3.15.0.3
KongKong Enteprise Gateway	Affected >=3.14.0.0 <3.14.0.12	Fixed in 3.14.0.12
KongKong Enteprise Gateway	Affected >=3.13.0.0 <3.13.0.9	Fixed in 3.13.0.9
KongKong Enteprise Gateway	Affected >=3.12.0.0 <3.12.0.10	Fixed in 3.12.0.10
KongKong Enteprise Gateway	Affected >=3.10.0.0 <3.10.0.17	Fixed in 3.10.0.17
KongKong Enteprise Gateway	Affected >=3.4.0.0 <3.4.3.29	Fixed in 3.4.3.29

AI-suggested

Patch versions are available that fix this vulnerability. Users should upgrade to versions 3.4.3.29 or later, 3.10.0.17 or later, 3.12.0.10 or later, 3.13.0.9 or later, 3.14.0.12 or later, or 3.15.0.3 or later as appropriate. Since this is not a cloud service, remediation requires applying these official fixes. No vendor advisory content was provided, so check the vendor's official security advisories for the latest patch information and guidance.

Description

A JWT signature verification vulnerability affects Kong components that perform JWT validation for MCP OAuth2 or DataKit integrations inside Kong API Gateway Enterprise. The affected code does not properly validate that the JWT signing algorithm is compatible with the type of key used for verification. As a result, an unauthenticated remote attacker may be able to craft a forged JWT that is incorrectly accepted as valid, leading to authentication bypass and potential compromise of confidentiality, integrity, and availability.

Impact

An unauthenticated remote attacker can exploit this vulnerability to bypass authentication mechanisms by presenting a forged JWT that is incorrectly accepted as valid. This can lead to unauthorized access, potentially compromising the confidentiality, integrity, and availability of the affected system.

Summary

This vulnerability (CVE-2026-14916) involves improper handling of unexpected data types (CWE-241) in the JWT signature verification process within Kong Enterprise Gateway. Specifically, the JWT validation code for MCP OAuth2 or DataKit integrations fails to ensure that the signing algorithm is compatible with the key type used. This allows attackers to create forged JWTs that bypass authentication controls. The issue affects multiple versions of Kong Enterprise Gateway starting from 3.4.0.0 up to but excluding certain patched versions in 3.4, 3.10, 3.12, 3.13, 3.14, and 3.15 branches.

CWE-241Improper Handling of Unexpected Data Type (opens in a new tab)
Base weakness
The product does not handle or incorrectly handles when a particular element is not the expected type, e.g. it expects a digit (0-9) but is provided with a letter (A-Z).
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).
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
OWASP ASVS 4.0.3
V1.5.1 (opens in a new tab)
Attack patterns
Passing Local Filenames to Functions That Expect a URL (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

developer.konghq.com/gateway/changelog/ (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 16 Sep 2026, 10:46 UTC

WeaknessesCWE-241

Technical details

References

Community reviews

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