VulnerabilityPublished 20 Nov 2025

CVE-2025-65226: Classic Buffer Overflow

Source CVE Database V5

Not known to be exploited · CVSS 4.3 Medium.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

4.3Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 17% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Adjacent
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: Low

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: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 20 Nov 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 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 restrict access to the router's management interface by limiting it to trusted internal networks only; disable remote management if not required.
Implement network segmentation to isolate routers from critical infrastructure and sensitive data systems.
Monitor network traffic and router logs for unusual requests to the /goform/saveParentControlInfo endpoint or unexpected device reboots.
Employ intrusion detection/prevention systems (IDS/IPS) capable of detecting buffer overflow attempts or anomalous HTTP requests targeting router management interfaces.
6. Consider replacing vulnerable devices with models from vendors with stronger security track records if patching is delayed. 7. Educate IT staff about this vulnerability to ensure rapid response if exploitation signs appear. 8. Use VPNs and strong authentication methods to secure remote access to network devices, reducing exposure to adjacent network attacks.

Description

CVE-2025-65226 is a medium-severity buffer overflow vulnerability affecting the Tenda AC21 router firmware version V16.03.08.16. The flaw exists in the handling of the deviceId parameter within the /goform/saveParentControlInfo endpoint. Exploitation requires network access with no authentication or user interaction needed, but the attack vector is remote and adjacent (AV:A). The vulnerability impacts availability by potentially causing device crashes or reboots but does not affect confidentiality or integrity. No known exploits are currently reported in the wild, and no patches have been released yet. European organizations using Tenda AC21 routers could face network disruptions if targeted. Mitigation involves network segmentation, restricting access to router management interfaces, and monitoring for unusual device behavior.

Impact

For European organizations, exploitation of this vulnerability could result in denial of service on affected Tenda AC21 routers, causing network outages or intermittent connectivity loss. This disruption can impact business operations, especially for small and medium enterprises relying on these routers for internet access or internal network segmentation. While the vulnerability does not directly compromise data confidentiality or integrity, the loss of availability can degrade productivity and may open secondary attack vectors if attackers use the router as a foothold. Organizations with remote or hybrid work setups that expose router management interfaces to wider networks are at increased risk. The absence of known exploits reduces immediate threat but does not eliminate the risk of future weaponization. The impact is more pronounced in environments where network redundancy is limited or where critical services depend on the affected devices.

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #11
The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
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.
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
OWASP Cheat Sheets
Docker Security (opens in a new tab)
XML Security (opens in a new tab)
OWASP ASVS 4.0.3
V5.4.1 (opens in a new tab)
V14.1.2 (opens in a new tab)
V13.3.1 (opens in a new tab)
Attack patterns
Buffer Overflow via Environment Variables (opens in a new tab)
Overflow Buffers (opens in a new tab)
Client-side Injection-induced Buffer Overflow (opens in a new tab)
Filter Failure through Buffer Overflow (opens in a new tab)
MIME Conversion (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/Madgeaaaaa/MY_VULN_2/blob/main/Tenda/VULN5.md (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 27 Nov 2025, 15:50 UTC

WeaknessesCWE-120

Technical details

References

Community reviews

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