CVE-2025-71413: Aviation VHF Link Control DoS Vulnerability

CVE-2025-71413 Overview

CVE-2025-71413 affects the Aviation Very High Frequency (VHF) Digital Link (VDL) Mode 2 protocol stack at the Link Control X.25 layers. Malformed or out-of-sequence frames trigger repeated link resets on affected receivers. The condition disrupts data link continuity between aircraft and ground stations. Attackers can deliver crafted frames remotely over radio frequency (RF) without physical access. Repeated resets increase controller and flight crew workload and reduce situational awareness. CISA published advisory ICSA-26-219-01 describing the issue. The weakness maps to CWE-754: Improper Check for Unusual or Exceptional Conditions.

Critical Impact
Remote RF-based frame manipulation forces repeated X.25 link resets, degrading aviation datalink availability and situational awareness for controllers and flight crews.

Affected Products

Aviation Very High Frequency Digital Link (VDL) Mode 2 implementations
X.25 Link Control layer components of affected avionics and ground datalink systems
Specific vendor and model details are enumerated in CISA advisory ICSA-26-219-01

Discovery Timeline

2026-08-07 - CVE-2025-71413 published to the National Vulnerability Database
2026-08-10 - Last updated in NVD database

Technical Details for CVE-2025-71413

Vulnerability Analysis

The vulnerability resides in the X.25 Link Control layers that carry Aviation VHF datalink traffic. Receivers do not adequately handle malformed frames or frames delivered outside the expected sequence. When such frames arrive, the stack forces a link reset to recover state. An attacker with an RF transmitter can generate these anomalous frames continuously. The resulting reset loop starves the link of usable throughput and prevents timely message exchange. Controllers and pilots lose access to Controller-Pilot Data Link Communications (CPDLC) and related services during the disruption. The immediate operational impact is added voice-radio workload and reduced situational awareness rather than data confidentiality loss.

Root Cause

The root cause is [CWE-754], improper checking for unusual or exceptional conditions in the X.25 frame handling logic. The implementation treats malformed or out-of-sequence frames as unrecoverable state errors. Each occurrence triggers a full link reset rather than selective frame rejection or rate-limited error recovery.

Attack Vector

The attack vector is network-adjacent over the VHF radio channel. An attacker requires an RF transmitter tuned to the VDL Mode 2 frequency range and the ability to encode X.25 frames. No credentials to end systems are required, though the CVSS vector notes low privileges due to protocol participation constraints. Attack complexity is high because the adversary must be within RF range and correctly frame the payload. The vulnerability targets availability only; confidentiality and integrity remain unaffected. Refer to CISA ICS Advisory ICSA-26-219-01 for protocol-level technical detail.

Detection Methods for CVE-2025-71413

Indicators of Compromise

Elevated rate of X.25 link resets and RESTART frames on VDL Mode 2 channels
Repeated SABM or DISC control frame sequences from a single or spoofed source address
Sudden drop in CPDLC message throughput without corresponding scheduled maintenance
Anomalous RF emissions on VDL Mode 2 frequencies from unregistered transmitters

Detection Strategies

Instrument datalink ground stations to log link-layer state transitions and reset counters
Correlate reset events across multiple ground receivers to identify RF-based attack patterns
Establish baselines for normal X.25 frame error rates and alert on statistical deviations
Coordinate with air navigation service providers to share telemetry on datalink disruptions

Monitoring Recommendations

Forward datalink infrastructure logs to a centralized SIEM for long-term correlation
Monitor RF spectrum for unauthorized transmitters operating in VDL Mode 2 bands
Track controller workload metrics as an operational proxy for datalink degradation

How to Mitigate CVE-2025-71413

Immediate Actions Required

Review CISA advisory ICSA-26-219-01 and identify affected avionics and ground systems in the operational fleet
Contact avionics and ground station vendors for firmware updates addressing X.25 frame validation
Ensure voice fallback procedures are current and rehearsed for datalink outages
Report suspected RF interference to national aviation and telecommunications regulators

Patch Information

Vendor-specific patches for affected avionics and ground datalink systems are coordinated through CISA advisory ICSA-26-219-01. Operators should consult their equipment manufacturers directly. No public patch identifiers were listed in the NVD entry at time of publication.

Workarounds

Increase RF spectrum monitoring around airports and en-route sectors to detect rogue transmitters
Coordinate with air traffic control to maintain voice-communication readiness during suspected attacks
Apply source-address filtering and rate limiting on X.25 control frames where the stack supports it
Direction-find and geolocate anomalous transmitters for enforcement action by spectrum regulators

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# Configuration example not applicable
# Mitigation requires vendor-supplied firmware updates for avionics
# and ground datalink systems. Consult ICSA-26-219-01 for specifics.