VulnerabilityPublished 18 Jun 2024Updated 1 Aug 2024

CVE-2024-6145: Actiontec WCB6200Q · Use of Externally-Controlled Format String

Affects Actiontec WCB6200QSource CVE Database V5

Not known to be exploited · CVSS 8.8 High.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.0 base score

8.8High

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

EPSS: 1.2% chance of exploitation in 30 days – higher than 68% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector: Adjacent
Attack Complexity: Low
Privileges Required: None
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: Adjacent: The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
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

Disclosed: evidence found.
CVE published 18 Jun 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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

AI-suggested

Immediately check for firmware updates from Actiontec and apply any patches addressing this vulnerability once available.
3. Disable remote management features if not required, especially HTTP access from untrusted networks. 4. Monitor network traffic for unusual HTTP requests containing suspicious Cookie headers or other anomalies indicative of exploitation attempts. 5. Employ intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics capable of detecting format string attacks targeting HTTP services. 6. Consider replacing affected devices with models that have a better security track record if patching or mitigation is not feasible. 7. Maintain regular backups of router configurations and monitor logs for signs of compromise. 8. Educate network administrators about this vulnerability and ensure incident response plans include steps for dealing with router compromises.

Description

Actiontec WCB6200Q Cookie Format String Remote Code Execution Vulnerability. This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of Actiontec WCB6200Q routers. Authentication is not required to exploit this vulnerability. The specific flaw exists within the HTTP server. A crafted Cookie header in an HTTP request can trigger the use of a format specifier from a user-supplied string. An attacker can leverage this vulnerability to execute code in the context of the HTTP server. Was ZDI-CAN-21417.

Impact

This vulnerability allows attackers to execute arbitrary code remotely on affected Actiontec WCB6200Q routers, potentially leading to full compromise of the device. The attacker can gain control over the router’s HTTP server process, which may allow them to intercept, modify, or redirect network traffic, disrupt network availability, or use the device as a foothold for further attacks within the network. Confidentiality is at risk as attackers could access sensitive information passing through the router. Integrity is compromised because attackers can alter router configurations or injected malicious payloads. Availability may be affected if the attacker disrupts router operations or causes denial of service. Given the router’s role as a network gateway, exploitation could have cascading effects on connected systems and networks, especially in enterprise or critical infrastructure environments. The ease of exploitation without authentication or user interaction significantly raises the threat level for organizations relying on this hardware.

CWE-134Use of Externally-Controlled Format String (opens in a new tab)
Base weaknessLikelihood of exploit: High
The product uses a function that accepts a format string as an argument, but the format string originates from an external source.
Requirements
Choose a language that is not subject to this flaw.
Implementation
Ensure that all format string functions are passed a static string which cannot be controlled by the user, and that the proper number of arguments are always sent to that function as well. If at all possible, use functions that do not support the %n operator in format strings.
Build and Compilation
Run compilers and linkers with high warning levels, since they may detect incorrect usage.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V5.4.2 (opens in a new tab)
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
Attack patterns
Format String Injection (opens in a new tab)
String Format Overflow in syslog() (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

zerodayinitiative.com/advisories/ZDI-24-808/ (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 26 Feb 2026, 03:01 UTC

WeaknessesCWE-134

Technical details

References

Community reviews

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