CVE-2026-21895 is a vulnerability in the rustcrypto `rsa` crate, an RSA implementation written in rust. This vulnerability allows the construction of an RSA private key to panic instead of returning an error when one of the primes is '1'. This flaw existed prior to version 0.9.10, which has been released to address this issue. Organizations using this crate should prioritize upgrading to the patched version to avoid potential disruptions.
The severity of this vulnerability is classified as low, with a CVSS score of 2.7. Although it does not pose a direct threat to confidentiality or integrity, it can impact availability, as the panic may disrupt normal operations. Therefore, organizations leveraging the rustcrypto library should assess their usage and apply the necessary updates promptly.
Currently, there are no known exploits for this vulnerability, and it has not been reported as actively exploited in the wild. However, the potential for abuse exists if an attacker can manipulate the key construction process. Thus, it is advisable for security teams to monitor their systems and apply the necessary patches to mitigate any risks.
Organizations should prioritize patching immediately. Remediation steps include upgrading to version 0.9.10 or higher of the rsa crate to ensure that the vulnerability is effectively mitigated.
For further details on the implementation and to ensure proper security practices, organizations can refer to the official GitHub repository and advisory.
Vulnerability Details
The `rsa` crate is designed to provide RSA cryptographic capabilities. The vulnerability arises when generating a RSA private key, where the system panics if one of the supplied primes is '1'. This behavior is not only unexpected but also detrimental to the stability of applications relying on this library. The vulnerability has been classified under CWE-703, which pertains to improper handling of exceptional conditions.
CVE-2026-21895 has a CVSS base score of 2.7, indicating low severity. The attack vector is network-based, the complexity is low, and no privileges or user interactions are required to trigger this vulnerability. The impacts on availability are low, while confidentiality and integrity are not affected.
The vulnerability was disclosed on January 8, 2026, and organizations should ensure they have upgraded their implementations to version 0.9.10 or later to address this issue.
Technical Analysis
The root cause of CVE-2026-21895 stems from a failure to properly validate the input parameters during the RSA key construction. Specifically, when one of the prime numbers is '1', instead of handling the error gracefully, the system enters a panic state. This leads to unexpected behavior and can disrupt the functionality of applications using this crate.
The attack vector is classified as network, as an attacker could potentially trigger this vulnerability through crafted inputs sent to a service that utilizes the rsa crate. The attack complexity remains low since no special conditions or privileges are required, making it accessible to various threat actors. User interaction is not required, which further increases the risk.
In terms of impacts, the availability of the system may be compromised if the panic occurs, leading to service interruptions. However, confidentiality and integrity are not directly impacted by this vulnerability.
Risk & Impact Analysis
The real-world risk associated with CVE-2026-21895 is primarily linked to the potential for system instability and service outages. Organizations relying on the rsa crate without upgrading to the patched version may face disruptions in their applications, affecting user experience and operational efficiency.
Despite the low severity rating, the blast radius could be significant depending on the deployment context. If this crate is used widely across critical services, the impact of a panic could lead to considerable downtime. Organizations must understand the implications of this vulnerability and take proactive measures to mitigate its effects.
The urgency for patching this vulnerability is moderate. While it is not actively exploited, the potential for disruption necessitates that organizations schedule remediation as part of their patch management cycle.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The versions affected by this vulnerability are all versions of the rsa crate prior to 0.9.10. Organizations should ensure they upgrade to this version or later to mitigate associated risks.
Mitigation & Remediation
To mitigate the risks associated with CVE-2026-21895, organizations should upgrade the rsa crate to version 0.9.10 or later. This version addresses the panic issue and improves the stability of applications relying on this library.
In cases where immediate upgrading is not feasible, consider implementing workarounds such as input validation to ensure that the primes provided for key generation are valid and not equal to '1'.
For further guidance on secure implementation practices, organizations can refer to the resources available on the AppSecure website, including their penetration testing services.
Detection Guidance
Organizations should monitor application logs for any indications of panic states caused by invalid RSA key constructions. Additionally, keep an eye on behavioral anomalies that may suggest attempts to exploit this vulnerability.
Network signatures should also be established to detect unusual patterns that may suggest malformed requests targeting the rsa crate.
AppSecure Threat Intelligence Insight
CVE-2026-21895 highlights the importance of thorough input validation and error handling in cryptographic libraries. As the reliance on cryptographic implementations increases, vulnerabilities like this can have far-reaching consequences.
Additionally, organizations can benefit from engaging in penetration testing methodology to assess the security posture of their applications.
In conclusion, CVE-2026-21895 serves as a reminder of the necessity of secure coding practices in cryptographic libraries, promoting vigilance and proactive security measures within development teams.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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