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Linksys E1700 EUVDEUVD-2026-97449

| CVE-2026-108892 CRITICAL
Stack-based Buffer Overflow (CWE-121)
2026-10-12 VulDB GHSA-cgfm-fxm5-56x9
9.3
CVSS 4.0 · Vendor: VulDB
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Reach router web interface
  2. Delivery
    Send crafted /goform/ssid1MACFilter request
  3. Exploit
    Overflow stack buffer via newap_text_%d
  4. Execution
    Hijack control flow on device
  5. Impact
    Execute code / crash router

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Stack buffer bounds checking
MITRE ATT&CK

1 technique across 1 tactic: Execution

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires the attacker to reach the router's HTTP administrative interface and send a request to the /goform/ssid1MACFilter endpoint (the Mac Filter configuration function) carrying an overlong newap_text_%d argument. The provided CVSS marks this PR:N (no privileges/unauthenticated), but this endpoint belongs to the device's admin web UI and in typical deployments is reachable only after authenticating to the router - confirm pre-auth reachability with the vendor/testing, as this is the single biggest limiter on real-world risk. Further limiting factors: the attacker must have network access to the management interface (LAN by default; only exploitable from the WAN/Internet if remote administration is enabled, which is not the default on most consumer routers), and the target must be the specific affected firmware (Linksys E1700 1.0.0.4.003). No special user interaction is required.

Impact

This is a genuine exploitation concern, though the signals are mixed and some key data is missing. The CVSS 4.0 vector (AV:N/AC:L/PR:N/UI:N) describes trivial remote, unauthenticated, low-complexity exploitation with full confidentiality, integrity, and availability impact, and a publicly disclosed POC exists (exploit maturity E:P in the vector corroborates this), so a working attack path is credible rather than theoretical. However, several real-world risk dampeners apply: no EPSS score was provided, so statistical exploitation likelihood cannot be quantified; the vulnerability is NOT in CISA KEV, so there is no evidence of active exploitation in the wild - only that exploit code has been published by the researcher (VulDB submission). A notable conflict: the provided CVSS asserts PR:N (unauthenticated), but the affected feature (/goform/ssid1MACFilter, a MAC-address-filtering configuration handler in the router's administrative web interface) is the kind of endpoint that is normally reachable only after logging into the admin panel - verify whether the endpoint is exposed pre-authentication, because if it requires an authenticated admin session the practical risk drops substantially. The vendor was contacted but did not respond and no patch is available, which raises residual risk for any still-deployed devices. Net assessment: a real, patch-unavailable buffer overflow with public exploit code on an end-of-life consumer router, but likely opportunistic/targeted rather than mass-exploited given the niche, aging product and absence of KEV/EPSS corroboration.

Exploit ScenarioDerived

An attacker with network reach to the router's web management interface sends a crafted HTTP request to /goform/ssid1MACFilter, supplying an overlong value in a newap_text_%d parameter that overflows a fixed-size stack buffer in the ssid1MACFilter handler. A publicly available POC (published on GitHub by the researcher) demonstrates the overflow, which can crash the device or, with a tailored payload, execute attacker-controlled code on the router. Because the CVSS vector lists PR:N the request is characterized as unauthenticated, though in practice reachability may depend on whether the admin interface is exposed.

Act Now Prioritize within 24-48h. Why: CRITICAL severity + public POC available.
1 public PoC No patch listed yet 0.6% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 12, 2026

A stack-based buffer overflow in the Mac Filter configuration handler of Linksys E1700 firmware 1.0.0.4.003 allows an attacker who can reach the router's administrative web interface to send an overlong newap_text_%d value to /goform/ssid1MACFilter and corrupt the stack, resulting in a crash and potentially code execution with the privileges of the device's web server. Publicly available exploit code exists (a detailed PoC is published on GitHub), but there is no CISA KEV listing and active exploitation has not been confirmed, so this should be treated as a credible but not yet observed attack. The vendor was contacted early about the disclosure and did not respond, so no patched firmware has been confirmed; the provided CVSS 4.0 vector rates it 9.3 with PR:N, while our independent assessment maps the same flaw to CVSS 3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, because the /goform endpoint sits behind the admin UI and is normally reachable only after authenticating - resolving that pre-auth vs. post-auth question is the single biggest factor in real-world risk.

RemediationAI

No vendor-released patch has been identified at time of analysis - Linksys did not respond to the disclosure, and no fixed firmware version is documented in any of the references, so remediation must currently rely on compensating controls until an update appears. The highest-value mitigation is to eliminate reachability of the administrative web interface from untrusted networks: confirm that remote management / WAN administration is disabled (it is off by default and should remain off), block inbound TCP 80/443 to the router's WAN address at any upstream firewall, and restrict LAN access to the management UI to trusted hosts or a dedicated management VLAN - the trade-off is that you lose the convenience of remote router administration. Because there is genuine ambiguity over whether /goform/ssid1MACFilter requires authentication, treat strong, unique admin credentials and prompt session timeout as a partial control rather than a fix; they only help if the endpoint is in fact post-auth reachable. If MAC filtering is not actively used, disabling the Mac Filter feature removes the attack surface on the affected /goform handler, at the cost of losing MAC-address-based access control (a weak control anyway, since MAC addresses are trivially spoofable). Monitor the VulDB entry at https://vuldb.com/vuln/416684 and https://www.linksys.com/ for a future firmware release, and if the device is no longer receiving updates, plan replacement or network isolation, since the publicly available exploit code at https://github.com/wudipjq/my_vuln/blob/main/Linksys3/vuln_66/66.md lowers the bar for exploitation by anyone who can reach the interface.

Affected VersionsENISA

E1700 1.0.0.4.003

Affected Packages

euvd e1700 no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The flaw is a classic CWE-121 stack-based buffer overflow in the embedded HTTP daemon of the Linksys E1700. The vulnerable function, ssid1MACFilter, handles the Mac Filter configuration page's form POST to /goform/ssid1MACFilter and copies the user-supplied newap_text_%d parameter into a fixed-size stack buffer without bounds checking (e.g., via strcpy/sprintf-style operations). Because the value is attacker-controlled and unbounded, an oversized argument overruns the buffer, overwrites adjacent stack memory including the saved return address, and can redirect execution - a standard path to denial of service (device crash/reboot) and, with a crafted payload, to remote code execution on the router's MIPS/ARM-class embedded environment. The affected product is captured by CPE cpe:2.3:a:linksys:e1700:*:*:*:*:*:*:*:* and the vulnerable build is 1.0.0.4.003. Network exposure is the key architectural consideration: the /goform interface is part of the LAN-side administrative web UI and is reachable from the WAN only when remote administration is explicitly enabled, which is not the default on consumer routers. The discrepancy between the supplied CVSS 4.0 vector (PR:N, implying unauthenticated reach) and our assessment (PR:L, implying the attacker must first authenticate to the admin UI) is not resolved by the available data and should be confirmed by testing against a live device.

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Severity by source

Vendor (VulDB) PRIMARY 9.3 CRITICAL
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:P
vuln.today AI 8.8 HIGH

Network-reachable low-complexity overflow with no user interaction; PR:L because the MAC-filter endpoint is an admin-panel feature typically behind authentication, yielding full code-execution impact on the device.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (VulDB).

CVSS VectorVendor: VulDB

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Vulnerable system: Confidentiality
High
Vulnerable system: Integrity
High
Vulnerable system: Availability
High
Subsequent system: Confidentiality
High
Subsequent system: Integrity
High
Subsequent system: Availability
High

Lifecycle Timeline

2
CVSS changed
Oct 12, 2026 - 14:22 NVD
10.0 (CRITICAL) 9.3 (CRITICAL)
CVE Published
Oct 12, 2026 - 13:30 cve.org
CRITICAL 9.3

DescriptionCVE.org

A vulnerability was determined in Linksys E1700 1.0.0.4.003. This vulnerability affects the function ssid1MACFilter of the file /goform/ssid1MACFilter of the component Mac Filter. This manipulation of the argument newap_text_%d causes stack-based buffer overflow. The attack may be initiated remotely. The exploit has been publicly disclosed and may be utilized. The vendor was contacted early about this disclosure but did not respond in any way.

Technical POC Analysis

The supplied evidence does not include an actual patch diff.

Full technical POC analysis - root cause, step-by-step exploitation and patch breakdown - is part of the Pro and Business plans.

Latest POC

1 public PoC link from github

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Executive ViewAI

Why It Matters

Linksys E1700 routers running firmware 1.0.0.4.003 are affected by a critical stack-based buffer overflow in the MAC filter web handler; publicly available exploit code exists and no vendor-released patch identified at time of analysis. Organizations using these devices could face network compromise or service disruption if an attacker reaches the administrative interface, so leadership should prioritize inventory, exposure reduction, and replacement planning while the vendor response remains unresolved.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis; interim mitigations include removing the router's administrative web interface from internet exposure, disabling remote management, restricting admin access to trusted networks, disabling MAC filtering if not needed, monitoring for /goform/ssid1MACFilter and overlong newap_text_%d requests, and replacing or isolating affected Linksys E1700 firmware 1.0.0.4.003 devices.

Threat Intelligence Overview

EPSS Score
0.6%
Top 52% exploitable
Prevalence
Low
aging end-of-life consumer SOHO router, single niche model
Social Media
3
Sightings
Data Quality
6 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity CRITICAL
CISA KEV No
Public POC Yes
EPSS 0.6%
Patch available No
Active threat No
Deciding rule
CRITICAL severity + public POC available
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Out-of-Cycle
Exploitation· derived
Poc
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact
High

Priority Score

67
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +46
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

A stack-based buffer overflow occurs when a program writes more data to a buffer located on the stack than it was allocated to hold.

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