VulnerabilityPublished 7 Aug 2025Updated 12 Aug 2025

CVE-2025-45765: ruby-jwt · Inadequate Encryption Strength

Source CVE Database V5

Not known to be exploited · CVSS 9.1 Critical.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.1 base score

9.1Critical

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 5% 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:H/I:N/A:H

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

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: 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: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 7 Aug 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

Immediate upgrade: Organizations should upgrade ruby-jwt to a stable, patched version that enforces strong encryption key sizes or addresses this vulnerability once available.
Enforce cryptographic policies: Independently enforce minimum key sizes and strong cryptographic algorithms at the application or infrastructure level, not relying solely on the library defaults.
Audit JWT usage: Review all applications using ruby-jwt to identify vulnerable versions and assess token encryption configurations.
Implement defense-in-depth: Use additional layers of security such as Web Application Firewalls (WAFs) to detect and block suspicious JWT-related traffic.
Monitor and log JWT validation failures and anomalies to detect potential exploitation attempts early.
Educate developers on secure JWT practices, including key management and token lifecycle.
If immediate upgrade is not feasible, consider disabling JWT features or replacing them with alternative secure authentication mechanisms temporarily.
Coordinate with cryptographic library providers (e.g., OpenSSL) to ensure their enforcement of key size policies is up to date and compatible with your environment.

Description

ruby-jwt v3.0.0.beta1 was discovered to contain weak encryption. NOTE: the Supplier's perspective is "keysize is not something that is enforced by this library. Currently more recent versions of OpenSSL are enforcing some key sizes and those restrictions apply to the users of this gem also."

Impact

For European organizations, this vulnerability poses a significant risk, especially for those relying on Ruby-based web applications or services that utilize the ruby-jwt library for authentication and session management. Exploitation could lead to unauthorized access to sensitive data, user impersonation, and service disruptions. Given the critical CVSS score and the fact that no privileges or user interaction are required, attackers can remotely exploit this vulnerability over the network. This can result in breaches of personal data protected under GDPR, leading to regulatory penalties and reputational damage. Additionally, availability impacts could disrupt critical business operations, especially in sectors like finance, healthcare, and government services where Ruby applications are prevalent. The weak encryption undermines the trustworthiness of JWT tokens, potentially allowing attackers to bypass authentication controls or cause denial of service by exploiting token validation failures. European organizations with legacy or beta versions of ruby-jwt are particularly vulnerable if they have not applied patches or mitigations.

Summary

CVE-2025-45765 is a critical vulnerability identified in the ruby-jwt library version 3.0.0.beta1, which is used for JSON Web Token (JWT) encoding and decoding in Ruby applications. The vulnerability stems from the use of weak encryption key sizes within the library. Although the library itself does not enforce key size restrictions, it relies on underlying cryptographic providers such as OpenSSL, which have started enforcing minimum key size requirements. This weak encryption (classified under CWE-326: Inadequate Encryption Strength) can lead to compromised confidentiality and availability of JWT tokens. Since JWTs are widely used for authentication and authorization in web applications, weak encryption can allow attackers to decrypt tokens, leading to unauthorized access or token forgery. The CVSS v3.1 score of 9.1 (critical) reflects the vulnerability's network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), high confidentiality impact (C:H), no integrity impact (I:N), and high availability impact (A:H). The absence of known exploits in the wild suggests it is a newly disclosed issue, but the potential for exploitation is significant given the ease of attack and critical impact. The vulnerability affects applications using the vulnerable ruby-jwt version, especially those that do not enforce strong cryptographic key sizes themselves or rely solely on the library's defaults. This weakness can lead to token decryption or denial of service by exploiting the weak encryption, undermining application security and availability.

CWE-326Inadequate Encryption Strength (opens in a new tab)
Class weaknessOWASP Top 10 A04:2025: Cryptographic Failures (opens in a new tab)
The product stores or transmits sensitive data using an encryption scheme that is theoretically sound, but is not strong enough for the level of protection required.
Architecture and Design
Use an encryption scheme that is currently considered to be strong by experts in the field.
OWASP Cheat Sheets
Cryptographic Storage (opens in a new tab)
Key Management (opens in a new tab)
Transport Layer Protection (opens in a new tab)
User Privacy Protection (opens in a new tab)
Password Storage (opens in a new tab)
OWASP ASVS 4.0.3
V2.8.3 (opens in a new tab)
V6.2.7 (opens in a new tab)
V6.2.4 (opens in a new tab)
Attack patterns
Encryption Brute Forcing (opens in a new tab)
Brute Force (opens in a new tab)
Protocol Analysis (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

Description

AI analysisMachine-generated, updated 15 Aug 2025, 01:04 UTC

WeaknessesCWE-326

Technical details

References

Community reviews

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