CVE-2025-31355VulnerabilityPublished 20 Aug 2025Updated 3 Nov 2025

CVE-2025-31355: Tenda AC6 V5.0 · Download of Code Without Integrity Check

Affects Tenda AC6 V5.0Source CVE Database V5

Not known to be exploited · CVSS 7.2 High.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

7.2High

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 22% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: High
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: High: The attacker is authorized with (i.e., requires) privileges that provide significant (e.g., administrative) control over the vulnerable component that could affect component-wide settings and files.
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 20 Aug 2025
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 2026-10-26.

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 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
Tenda AC6 V5.0	Affected =02.03.01.110	Fixed in–

AI-suggested

1. Immediately restrict administrative access to the Tenda AC6 V5.0 routers by limiting management interfaces to trusted networks and using strong authentication methods. 2. Monitor network traffic and device logs for unusual firmware update attempts or unauthorized file uploads. 3. Disable remote firmware update capabilities if not strictly necessary or restrict them to secure channels and authenticated sessions. 4. Implement network segmentation to isolate vulnerable devices from critical infrastructure and sensitive data. 5. Engage with Tenda support channels to obtain official patches or firmware updates addressing this vulnerability as soon as they become available. 6. If patching is delayed, consider replacing affected devices with alternative hardware that has verified secure update mechanisms. 7. Conduct regular security audits and vulnerability assessments on network devices to detect and remediate similar issues proactively.

Description

A firmware update vulnerability exists in the Firmware Signature Validation functionality of Tenda AC6 V5.0 V02.03.01.110. A specially crafted malicious file can lead to arbitrary code execution. An attacker can provide a malicious file to trigger this vulnerability.

Impact

For European organizations, exploitation of this vulnerability could lead to severe consequences including unauthorized control over network routing devices, interception of sensitive communications, and disruption of network services. This can compromise confidential data, degrade service availability, and undermine trust in network infrastructure. Critical sectors such as finance, healthcare, government, and telecommunications that rely on secure and stable network equipment are particularly vulnerable. The ability to execute arbitrary code on routers can facilitate lateral movement within networks, enabling attackers to escalate attacks or deploy ransomware. Given the widespread use of Tenda routers in small to medium enterprises and some consumer environments across Europe, the potential impact spans from localized business disruptions to broader supply chain risks if compromised devices are used as attack vectors.

Summary

CVE-2025-31355 is a vulnerability identified in the firmware signature validation mechanism of the Tenda AC6 V5.0 router, specifically in firmware version V02.03.01.110. The core issue relates to CWE-494, which involves downloading code without proper integrity checks. In this case, the router’s firmware update process fails to adequately verify the authenticity and integrity of the firmware image or update files. An attacker who can supply a maliciously crafted file—likely through administrative or privileged access—can exploit this flaw to execute arbitrary code on the device. This could allow the attacker to alter router configurations, intercept or redirect network traffic, or use the device as a foothold for further network compromise. The CVSS 3.1 score of 7.2 reflects high severity, with network attack vector (AV:N), low attack complexity (AC:L), but requiring high privileges (PR:H), no user interaction (UI:N), and impacting confidentiality, integrity, and availability (C:H/I:H/A:H). Although no public exploits are currently known, the vulnerability’s nature and impact make it a critical concern for network security. The lack of a patch at the time of reporting increases urgency for interim mitigations.

CWE-494Download of Code Without Integrity Check (opens in a new tab)
Base weaknessLikelihood of exploit: MediumOWASP Top 10 A08:2025: Software or Data Integrity Failures (opens in a new tab)
The product downloads source code or an executable from a remote location and executes the code without sufficiently verifying the origin and integrity of the code.
Implementation
Perform proper forward and reverse DNS lookups to detect DNS spoofing.
Architecture and Design · Operation
Encrypt the code with a reliable encryption scheme before transmitting.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
OWASP Cheat Sheets
Docker Security (opens in a new tab)
XML Security (opens in a new tab)
Software Supply Chain Security (opens in a new tab)
Infrastructure as Code (opens in a new tab)
OWASP ASVS 4.0.3
V1.14.2 (opens in a new tab)
V10.3.1 (opens in a new tab)
V13.3.2 (opens in a new tab)
Attack patterns
Malicious Software Download (opens in a new tab)
Malicious Software Update (opens in a new tab)
Malicious Automated Software Update via Redirection (opens in a new tab)
Malicious Manual Software Update (opens in a new tab)
Open-Source Library Manipulation (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 4 Nov 2025, 02:11 UTC

WeaknessesCWE-494

Technical details

References

Community reviews

Related threats