NR Modem Input Validation Flaw Enables Remote DoS

In nr modem, there is a possible improper input validation. This could lead to remote denial of service with System execution privileges needed.

Casky was already ahead

This CVE exploits attack patterns that Casky's 322matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.

Analysis

CVE-2026-21548 represents a critical input validation vulnerability in NR (New Radio) modem implementations that allows attackers to trigger remote denial of service conditions. The vulnerability stems from improper handling of user-supplied input, classified under CWE-20, which fails to properly validate or sanitize data before processing. This affects telecommunications infrastructure and connected devices relying on NR modem technology, potentially impacting mobile networks, IoT deployments, and critical communication systems. While the CVSS score of 7.5 indicates high severity, the requirement for System execution privileges somewhat limits immediate exposure, though the remote attack vector significantly increases risk across distributed modem populations.

Casky.ai's 322 mapped skills leverage Claude AI's extended reasoning to correlate attack patterns across two distinct MITRE ATT&CK techniques: TA0001 (Reconnaissance) and TA0043 (Reconnaissance via network traffic analysis and vulnerability scanning). Practitioners using the platform would observe detection capabilities spanning initial access reconnaissance activities and exploitation patterns that probe input handling boundaries. The skills enable identification of malformed packet sequences, anomalous protocol state transitions, and input mutation attempts targeting the validation logic—signatures typical of pre-exploitation reconnaissance. By mapping these behaviors against the 754-skill framework, security teams gain visibility into the adversary kill chain stages preceding actual DoS execution, allowing for earlier intervention during the information gathering and weaponization phases before system privileges are leveraged to achieve denial of service impact.

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Casky Risk Score

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EPSS Probability

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Shodan Exposure

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GreyNoise Signal

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Composite risk scoring from EPSS, CISA KEV, Shodan, and GreyNoise — 21 security APIs correlated into a single Casky Risk Score. Coming in Casky Pro. Join early access →

322 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-21548.

Abuse of Public-Facing API: Mobile API Abuse

mobile security · low

Run

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

MITRE ATT&CK Techniques

TA0001 TA0043

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