VulnerabilityPublished 1 Oct 2025Updated 28 Oct 2025

CVE-2025-59685: Kazaar 1.25.12 allows a JWT with none in the alg field

Source CVE Database V5

Not known to be exploited · CVSS 5.3 Medium.

Data as of 26 Oct 2026, 15:59 UTC

CVSS 3.1 base score

5.3Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 24% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
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: None: The vulnerable system can be exploited without any interaction from any user.
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 1 Oct 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

AI-suggested

Immediately audit all systems using Kazaar to identify affected versions, specifically version 1.25.12.
Apply official patches or updates from Kazaar vendors as soon as they become available to fix the JWT validation flaw.
If patches are not yet available, implement custom JWT validation logic that explicitly rejects tokens with the 'alg' field set to 'none'.
Review and enhance JWT handling libraries or middleware configurations to enforce strict algorithm validation and signature verification.
Conduct penetration testing and code reviews focusing on authentication mechanisms to detect similar weaknesses.
Monitor network traffic and logs for suspicious JWT tokens or authentication anomalies indicative of exploitation attempts.
Educate developers and security teams about secure JWT implementation best practices to prevent recurrence.
Consider deploying Web Application Firewalls (WAFs) with rules to detect and block JWT tokens with 'alg' set to 'none' as a temporary mitigation.

Description

Kazaar 1.25.12 allows a JWT with none in the alg field.

Impact

For European organizations, this vulnerability could lead to unauthorized access to sensitive systems or data if Kazaar is used within their environments, particularly in applications relying on JWT for authentication or authorization. The confidentiality of user data or internal communications could be compromised, potentially exposing personal data protected under GDPR. Although the vulnerability does not affect integrity or availability directly, unauthorized access can lead to further exploitation or data leakage. Organizations in sectors such as finance, healthcare, or government that use Kazaar or integrate it into critical services are at higher risk. The lack of required authentication or user interaction means attackers can exploit this remotely, increasing the threat surface. The medium severity score suggests a moderate impact, but the ease of exploitation warrants timely mitigation to prevent escalation or lateral movement within networks.

References

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