CVE-2018-4063ExploitPublished 13 Dec 2025

CISA Adds Actively Exploited Sierra Wireless Router Flaw Enabling RCE Attacks

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Authoritative record:CVE-2018-4063· High 8.8

Exploited in the wild · KEV due 2 Jan 2026 : apply the vendor's fix or mitigations to AirLink ALEOS now.

Data as of 20 Dec 2025, 11:41 UTC

CVSS 3.1 base score

8.8High

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

KEV deadline: 2 Jan 2026 US federal agencies must patch by this date; a sensible deadline for everyone else. Other KEV due dates

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
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: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
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: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to 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

t = 0 is the CVE’s publication on cve.org

Disclosed: evidence found.
CVE published 6 May 2019
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: evidence found.
Listed in CISA KEV 6.6 years after disclosure
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

CVE published
on cve.org
6 May 201918:43 UTC, t = 0
Added to CISA KEV (opens in a new tab)
exploitation confirmed
12 Dec 2025, 6.6 years after disclosure
KEV remediation due
US federal deadline
2 Jan 2026, 6.7 years after disclosure

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA KEV (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 1 Nov 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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

Affected software

Product	Affected	Fixed in
Sierra Wireless	Affected =Sierra Wireless AirLink ES450 FW 4.9.3	Fixed in–

AI-suggested

European organizations should prioritize immediate mitigation steps beyond generic patching advice. First, identify all Sierra Wireless AirLink ALEOS routers in use, especially versions known to be vulnerable (e.g., firmware 4.9.3). Since affected devices have reached end-of-support, organizations should plan for device replacement with supported models that have patched this vulnerability. Where replacement is not immediately feasible, implement strict network segmentation to isolate vulnerable routers from critical systems and limit access to management interfaces. Enforce strong authentication and access controls on router management portals, including multi-factor authentication where possible. Monitor network traffic for anomalous HTTP requests targeting /cgi-bin/upload.cgi and unusual file upload activities. Deploy intrusion detection/prevention systems (IDS/IPS) tuned to detect exploitation attempts of CVE-2018-4063. Conduct regular audits of router firmware versions and configurations. Engage with vendors for any available security advisories or mitigations. Finally, incorporate these routers into incident response plans, preparing for potential compromise scenarios.

Description

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Friday added a high-severity flaw impacting Sierra Wireless AirLink ALEOS routers to its Known Exploited Vulnerabilities (KEV) catalog, following reports of active exploitation in the wild. CVE-2018-4063 (CVSS score: 8.8/9.9) refers to an unrestricted file upload vulnerability that could be exploited to achieve remote code

Impact

For European organizations, especially those operating critical infrastructure, manufacturing, transportation, and utilities, this vulnerability poses a significant risk. Sierra Wireless AirLink ALEOS routers are commonly deployed in industrial and operational technology environments across Europe. Successful exploitation can lead to complete compromise of the router, enabling attackers to execute arbitrary commands with root privileges, potentially disrupting network communications, exfiltrating sensitive data, or deploying malware such as botnets or cryptocurrency miners. This can result in operational downtime, financial losses, reputational damage, and regulatory penalties under frameworks like GDPR and NIS Directive. The vulnerability's presence in OT environments raises concerns about safety and reliability of critical services. Additionally, the end-of-support status of affected devices complicates remediation efforts, increasing the window of exposure. Attackers leveraging this flaw can also use the compromised routers as pivot points for broader network intrusions, escalating the threat to enterprise IT environments connected to OT networks.

Summary

CVE-2018-4063 is a remote code execution vulnerability discovered in the Sierra Wireless AirLink ALEOS routers, particularly affecting the ACEManager's upload.cgi functionality. The flaw stems from an unrestricted file upload mechanism that lacks proper validation and access controls, allowing an authenticated attacker to upload files with arbitrary names. If the uploaded file overwrites an existing executable file on the device, such as fw_upload_init.cgi or fw_status.cgi, the attacker can execute arbitrary code with root privileges because ACEManager runs as root. This vulnerability was initially reported by Cisco Talos in 2018 and publicly disclosed in 2019. Despite its age, active exploitation has been observed recently, leading CISA to add it to its Known Exploited Vulnerabilities catalog in December 2025. Attackers exploit this by sending specially crafted HTTP requests to the /cgi-bin/upload.cgi endpoint, uploading malicious payloads that can compromise the router and potentially the broader network. The vulnerability is particularly dangerous in operational technology (OT) environments where these routers are prevalent, as attackers can deploy botnets or cryptocurrency miners, disrupt communications, or gain persistent access. The vulnerability is compounded by the end-of-support status of affected devices, limiting vendor patches and increasing exposure. A threat cluster named Chaya_005 was observed weaponizing this flaw in early 2024, although no recent successful exploits have been reported. The vulnerability's exploitation requires authentication but can lead to full device compromise and lateral movement within networks.

References

thehackernews.com/2025/12/cisa-adds-actively-exploited-sierra.html (opens in a new tab)

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Exploitation evidence

Timeline

What to do

Affected software

Description

AI analysisMachine-generated, updated 13 Dec 2025, 14:34 UTC

References

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