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CVE-2026-17518NVD status: Awaiting Analysis

Router: Stack-based Buffer Overflow

Published Updated By the CyberSecBulletin desk

CVE-2026-17518 is a high-severity stack-based buffer overflow vulnerability in Router from ASUS, with a CVSS 4.0 base score of 8.2 out of 10. It can be exploited from the same local network by an attacker with administrator privileges, without any action from a user. Affected Router versions: ASUSWRT 3.0.0.4_386 series; ASUSWRT 3.0.0.4_388 series. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.19% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of Router you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on asus.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
ASUSRouterASUSWRT 3.0.0.4_386 series; ASUSWRT 3.0.0.4_388 seriesNot stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
AdjacentThe attacker must be on the same local network segment.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Attack requirements
NoneThe attack does not depend on a particular deployment or configuration.
Privileges required
HighAdministrator-level access is required first.
User interaction
NoneNo action by a victim is required.
Confidentiality (vulnerable system)
NoneNo loss of confidentiality on the vulnerable system.
Integrity (vulnerable system)
HighSerious loss of integrity on the vulnerable system.
Availability (vulnerable system)
HighSerious loss of availability on the vulnerable system.
Confidentiality (other systems)
NoneNo loss of confidentiality on systems beyond the vulnerable one.
Integrity (other systems)
NoneNo loss of integrity on systems beyond the vulnerable one.
Availability (other systems)
HighSerious loss of availability on systems beyond the vulnerable one.

Vector: CVSS:4.0/AV:A/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. Scored by CNA.

Official description

Buffer Copy without Checking Size of Input in certain ASUS router models allows an adjacent authenticated user to corrupt device operations and cause a denial of service via an HTTP request with input exceeding the expected length. Refer to the ' Security Update for ASUS Router Firmware' section on the ASUS Security Advisory for more information.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Stack-based Buffer Overflow

The product writes past the end of a buffer that was allocated on the stack.

How developers prevent this class of flaw

  • 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 checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
  • Use an abstraction library to abstract away risky APIs. Not a complete solution.
  • Implement and perform bounds checking on input.

More Stack-based Buffer Overflow vulnerabilities (CWE-121)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).

References

Other vulnerabilities in Router

All Router vulnerabilities

Recent Stack-based Buffer Overflow vulnerabilities

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