Unauthenticated MAVLink remote shell

1. Summary

PX4 Autopilot’s MAVLink communication interface performs no cryptographic authentication of incoming messages by default. When MAVLink 2.0 message signing is disabled (the default state), an attacker who can reach the MAVLink interface over the network or radio can send a crafted SERIAL_CONTROL message that opens an interactive shell on the flight controller [1][7]. From that shell the attacker executes arbitrary commands on the highest-authority component of the aircraft, enabling them to disarm, alter the mission, command flight, crash the vehicle, or read onboard data [1][6]. The defect is tracked as CWE-306 (Missing Authentication for Critical Function) [1].

2. Affected products & versions

3. The vulnerability in detail

The flaw lives in how PX4 Autopilot handles inbound MAVLink messages. MAVLink is the messaging protocol that PX4 uses to talk to ground control stations, companion computers, and other peripherals. By design, MAVLink carries no cryptographic authentication of the sender by default [1][4]. The only protection mechanism against message forgery, MAVLink 2.0 message signing, is turned off in the default configuration. When signing is off, the PX4 receiver does not reject unsigned messages — it acts on any message it receives, without any verification that the sender is a legitimate, authorized party [1][4]. This is the root cause: a critical control surface is exposed with no gate on who is allowed to reach it. Both the NVD record and the vendor’s own signing documentation confirm that authentication is opt-in and absent by default [1][4].

The specific critical function that turns this trust gap into full compromise is the SERIAL_CONTROL MAVLink message [1][7]. SERIAL_CONTROL is intended to bridge a serial port through MAVLink, and in PX4 it can be used to reach an interactive system shell on the flight controller. Because no authentication is enforced, an unauthenticated party can invoke this bridge and obtain a shell — and the shell runs on the flight controller, which is the highest-authority component of the vehicle [1]. Once an attacker holds a shell there, they are no longer merely spoofing individual commands; they command the device that governs arming state, mission execution, and flight [7]. From that position the attacker can disarm the vehicle mid-operation, rewrite the mission plan, issue direct flight commands, deliberately crash the aircraft, or exfiltrate telemetry, mission data, and onboard storage [1][6][8].

The mechanism is triggered under a narrow and realistic set of preconditions. The attacker needs network or radio reach to the MAVLink interface, no credentials, and no user interaction, and the target must have signing disabled — which is the default [1][7]. In practice, MAVLink traffic is commonly carried over UDP. PX4’s default UDP ports are 14550 for the ground control station link and 14540 for the offboard/companion link, and these are the plausible transport for the attack path; however, the specific port numbers are the standard PX4 defaults and are (not enumerated in public advisories) rather than being stated in the exploitation writeups. What the sources do establish is that the interface is network/radio-reachable and that no credentials are required [1][7]. The finding was demonstrated against a build of PX4 Autopilot v1.16.0 SITL (software-in-the-loop) [1][3]. Importantly, this is a software-based flaw, not a hardware defect, which means it is intrinsic to the deployed firmware rather than to any particular airframe [6].

The step-by-step exploitation chain is short and deterministic [1][7]:

1. Reach the MAVLink interface over the network or radio, presenting no credentials.
2. Because signing is off, the PX4 receiver accepts the unsigned message stream.
3. Send a crafted SERIAL_CONTROL message.
4. PX4 opens an interactive shell, unauthenticated, on the flight controller.
5. Run arbitrary shell commands on the highest-authority component.
6. Disarm, alter the mission, command flight, crash the vehicle, or exfiltrate onboard data.

The chain is conceptually simple and requires no bypass of any authentication (there is none to bypass), so the barrier to independent weaponization is low.

The CWE at play, CWE-306 (Missing Authentication for Critical Function), describes exactly this class of defect: a function that performs a security-relevant or high-authority action — here, opening a shell on the flight controller — is reachable without the software first establishing that the requester is who they claim to be and is permitted to make the request. This CWE assignment is drawn from the authoritative NVD and CVE.org records [1][2]; sources [6][7] describe the same missing-signature/missing-authentication root cause but do not cite the CWE identifier. The signing mechanism that would close this gap provides authentication and integrity, but notably not encryption; it verifies that a message came from a holder of the shared signing key and was not tampered with, but does not conceal the traffic [4]. That distinction matters for remediation: enabling signing stops unauthenticated command injection but does not by itself protect against eavesdropping.

4. Discovery & timeline

The vulnerability was discovered and reported by Dolev Aviv of Cyviation [2][3]. Cyviation announced the finding publicly via a Business Wire press release framing it as a critical flaw in widely used UAV/drone software with potential for hacker takeover [5]. The coordinated disclosure resulted in CISA ICS advisory ICSA-26-090-02, published 2026-03-31, with ICS-CERT acting as the assigning CNA [2][3]. The CVE record CVE-2026-1579 was published on the same date, 2026-03-31 [2]. A specific patched firmware version is not documented in the sources; the vendor’s remediation is configuration-based (enable MAVLink 2.0 signing and isolate the interface) rather than a code fix version [3][4].

5. Technical reference

• CVE: CVE-2026-1579 [1][2]
• CWE: CWE-306 — Missing Authentication for Critical Function [1][2]
• CVSS v3.1: 9.8 — vector AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H [1]. Every access metric is at its most permissive: AV:N (reachable over the network), AC:L (no special conditions), PR:N (no privileges), UI:N (no user interaction), with C:H/I:H/A:H (total loss of confidentiality, integrity, and availability of the affected component). The scope is Unchanged (S:U), which — as discussed in Section 6 — understates the real-world blast radius.
• CVSS v4.0: 9.3 [1][3].
• Affected build: PX4 Autopilot v1.16.0 SITL (v1.16.0_SITL_latest_stable) [1][3].
• Assigning CNA: ICS-CERT [1][2].
• Transport note: MAVLink is commonly carried over UDP; PX4’s standard default ports are 14550 (GCS) and 14540 (offboard/companion). These are well-known PX4 defaults but are (not enumerated in public advisories).
• Code/commit refs: none documented; no fixing commit is cited in the available sources.

6. Consequence & CFSE path analysis

Real-world consequence: an unauthenticated attacker within network or radio range of a PX4 aircraft can seize interactive control of the flight controller and physically command, disarm, or crash the vehicle — and separately can steal its telemetry, mission plans, and onboard data. This is a safety-of-flight consequence affecting critical-infrastructure sectors including transportation, emergency services, and the defense industrial base [3].

Why the CFSE Path Score diverges from CVSS. CVSS scores the technical severity against a single “affected component” with Scope Unchanged, producing a 9.8/9.3 that, while high, treats the outcome as a conventional confidentiality/integrity/availability loss. CFSE instead decomposes the CVE into distinct consequence paths and bands each against the tangible real-world outcome, which surfaces a physical-safety consequence CVSS does not directly represent.

The CFSE analysis decomposes CVE-2026-1579 into two consequence paths. The band codes and requirement flags below are CFSE scoring; the rationale for each band is given inline:

• Dominant path — DEVICE_CONTROL_SAFETY — banded EMERGENCY. An unauthenticated attacker with network/radio reach to the MAVLink interface sends a single crafted SERIAL_CONTROL message to open an interactive shell on the flight controller (the highest-authority component), letting them disarm, alter the mission, command flight, or crash the vehicle. The bands (RE4/EC4/AT4/PH4/CH4/SR4/SX4) reflect maximal reach, ease, and attacker control at fleet scale — the same default-off condition and protocol-level entry recur across every deployment of the affected firmware — with only configuration/hardening recovery available (OR3, since no patched version ships and remediation is operator-side).
• Supporting path — DATA_PRIVACY — capped at CRITICAL. The same unauthenticated shell entry exfiltrates telemetry, mission plans, and onboard storage (DP3, PH0) but is capped because it does not independently drive a physical/safety consequence.

Both paths note that a patch/mitigation is available (LS:PATCH_AVAILABLE, i.e. the signing/isolation configuration mitigation) and cite the NVD/ICSA record. The overall path_verdict is EMERGENCY, driven by the dominant safety path. The record is marked UNDER (understated relative to the published CVSS treatment) because CVSS Scope=Unchanged does not capture the physical-safety blast radius; on that basis Requirements 1, 2, and 7 are flagged as missed (the safety-consequence, blast-radius, and format/requirement checks respectively, per the CFSE requirement numbering).

Verdict: EMERGENCY.

7. Remediation & mitigations

The vendor’s remediation is configuration- and deployment-based, and it maps directly to the defect:

• Enable MAVLink 2.0 message signing. This is the specific fix for the missing-authentication root cause: signing adds cryptographic authentication and integrity so PX4 rejects unsigned/forged messages, closing the unauthenticated SERIAL_CONTROL path [3][4]. In PX4, signing is enabled via the SETUP_SIGNING message, and the signing key is stored at /mavlink/mavlink-signing-key.bin [4]. Note that signing cannot be changed while the vehicle is armed, so it must be configured before operations [4].
• Restrict and segment the MAVLink interface. Limit network/radio reachability of the MAVLink link (e.g., isolation/segmentation) so the SERIAL_CONTROL entry point is not exposed to untrusted parties [3][6]. This is the second half of the vendor guidance and provides defense in depth even where signing is in place — directly reducing the “network or radio reach” precondition the attack depends on.
• Understand the residual limits of signing. Signing provides authentication and integrity but not encryption, so it does not protect against eavesdropping on MAVLink traffic [4]. It also does not protect against SD-card key extraction, and it does not cover the allowlisted unsigned messages — HEARTBEAT, RADIO_STATUS, ADSB_VEHICLE, and COLLISION — which remain acceptable unsigned and could still be spoofed [4]. Operators relying on signing to close the SERIAL_CONTROL path should account for these gaps, since they define the residual attack surface after remediation.
• Follow the PX4 security hardening guidance referenced by the CVE record for broader deployment hardening [4][6].

No fixed firmware version is documented; remediation is achieved through the above configuration hardening rather than a version upgrade in the available sources [3][4].

8. Sources

1. NVD — CVE-2026-1579 — NIST NVD — https://nvd.nist.gov/vuln/detail/CVE-2026-1579 — Authoritative record: description of the unauthenticated MAVLink/SERIAL_CONTROL shell path, CWE-306, CVSS v3.1 9.8 and v4.0 9.3, affected PX4 v1.16.0 SITL, CNA = ICS-CERT. Credibility: primary-advisory.
2. CVE Record CVE-2026-1579 (CVE.org / CVE Services API) — CVE.org (MITRE CVE Program, ICS-CERT CNA) — https://cveawg.mitre.org/api/cve/CVE-2026-1579 — Canonical CVE record confirming CNA, CWE, both CVSS vectors, affected build, reference set, and researcher/publication date. Credibility: primary-advisory.
3. PX4 Autopilot | CISA ICS Advisory ICSA-26-090-02 — CISA / ICS-CERT — https://www.cisa.gov/news-events/ics-advisories/icsa-26-090-02 — Official government advisory (2026-03-31, the CNA source): scores, CWE, affected version, affected sectors, researcher attribution, and mitigation guidance; no known public exploitation. Credibility: primary-advisory (corroborated across NVD, CVE.org, and press).
4. PX4 MAVLink Message Signing (official PX4 documentation) — PX4 / Dronecode — https://docs.px4.io/main/en/mavlink/message_signing — Authoritative vendor fix/hardening guidance: signing as authentication/integrity (not encryption), SETUP_SIGNING, key storage path, unsigned allowlist, armed-state restriction, and explicit limitations. Credibility: primary-advisory.
5. CYVIATION Discovers Critical Security Flaw in Popular UAV and Drone Software (Business Wire press release) — Cyviation (via Business Wire / StreetInsider) — https://www.streetinsider.com/Business+Wire/CYVIATION+Discovers+Critical+Security+Flaw+in+Popular+UAV+and+Drone+Software,+Preventing+Potential+Hacker+Takeovers/26279664.html — Primary disclosure announcement from the discovering firm; researcher/vendor attribution and disclosure framing. Credibility: researcher-primary (indexed and corroborated).
6. Major PX4 drone software vulnerability raises hijacking concerns — DroneDJ — https://dronedj.com/2026/04/07/px4-autopilot-drone-software-cybersecurity/ — Domain-specific technical press: confirms Cyviation as discoverer, missing-signature root cause, full navigation-control impact, CVSS 9.8, software-based nature, no confirmed exploitation, and mitigations. Credibility: reputable-press.
7. Ghost in the Drone: Unauthenticated Shell Access in PX4 Autopilot’s 9.8 CVSS Nightmare — SecurityOnline (securityonline.info) — https://securityonline.info/px4-autopilot-mavlink-vulnerability-cve-2026-1579/ — Technical writeup of the SERIAL_CONTROL shell mechanism and the unauthenticated MAVLink attack path; describes the missing-authentication root cause and signing mitigation. Does not enumerate specific UDP port numbers or cite the CWE identifier. Credibility: reputable-press.
8. Critical PX4 Autopilot Vulnerability Let Attackers Gain Control Over the Drones — Cybersecurity News — https://cybersecuritynews.com/px4-autopilot-vulnerability/ — General security-press corroboration: unauthenticated MAVLink command execution, CVSS 9.8, affected sectors, Cyviation/CISA attribution, mitigations, no known exploitation. Credibility: reputable-press.