CVE-2026-91018

Description

lwIP (Lightweight IP) has a double free vulnerability, which could crash the system, cause a DoS, memory corruption, or allow code execution on the victim system.

Overview

State: PUBLISHED
Assigner (CNA): icscert
CVSS severity: HIGH
CVSS score: 8.7 / 10
CVSS vector: CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Effective score: 8.7 / 10 HIGH source: CNA overview
CWE(s): CWE-415
Reserved: 2026-09-14
Published: 2026-09-22 20:25 UTC
Last updated: 2026-09-22 20:25 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/91xxx/CVE-2026-91018.json
Linked Threat: CVE-2026-91018 — Double Free in lwIP (lightweight IP)

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2026-09-22 21:17:33 UTC
NVD last modified: 2026-09-22 21:17:33 UTC
NVD CVSS v3.1: 8.8 / 10 HIGH source: ics-cert@hq.dhs.gov
NVD CVSS vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploitability subscore: 2.8 / 10
Impact subscore: 5.9 / 10

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-84864
Assigner: icscert
Published: Sep 22, 2026, 8:25:33 PM
Updated: Sep 22, 2026, 8:25:33 PM
EUVD base score (CVSS 4.0): 8.7 / 10
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
EUVD-reported EPSS: 0.0000
Vendors: lwIP
Products: lwIP API (2.0.1 ≤2.2.1)
Aliases: GHSA-rmx4-24pf-8x6h

ENISA description: lwIP (Lightweight IP) has a double free vulnerability, which could crash the system, cause a DoS, memory corruption, or allow code execution on the victim system.

EUVD references (3)

Affected products (1)

Vendor	Product	Versions	Platforms
lwIP	lwIP API	`2.0.1` (affected)	—

Vendor references (3)

References embedded in the original CVE record by the assigning CNA.

Web references (0)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

No web references attached yet.

NVD-tagged references (3)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

https://cgit.git.savannah.gnu.org/cgit/lwip.git ics-cert@hq.dhs.gov
https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-265-02.json ics-cert@hq.dhs.gov
https://www.cisa.gov/news-events/ics-advisories/icsa-26-265-02 ics-cert@hq.dhs.gov

Remediations (10)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

lwIP Double Free Vulnerability CVE-2026-91018 Threatens Critical ...

web:aviatrix.ai

Attackers exploit the CVE-2026-91018 double free vulnerability in lwIP to gain initial access to IoT/OT systems via adjacent network access. Following successful exploitation, attackers escalate privileges through memory corruption, move laterally across unencrypted network segments, establish command and control channels, exfiltrate sensitive industrial data, and cause operational disruption ...

2026-09-23 15:14 UTC
Security Advisory - Action Required - Active Exploitation of CVE-2026 ...

web:blog.checkpoint.com

CVE - 2026 -93616 is a newly discovered zero-day vulnerability in Security Management, and a fix is available now as part of this advisory. Fixes are available for both vulnerabilities. Customers running affected versions should install the applicable fixes immediately. Affected versions and remediation instructions are detailed below.

2026-09-23 15:14 UTC
Microsoft and Adobe Patch Tuesday, August 2026 Security Update Review

web:blog.qualys.com

The August 2026 Microsoft Patch Tuesday release delivers security fixes for vulnerabilities affecting a wide range of Microsoft products and services.

2026-09-23 15:14 UTC
CVE-2026-91018 - Exploits & Severity - Feedly

web:feedly.com

A vulnerability was found in lwIP up to 2.2.1 . It has been declared as critical . This impacts an unknown function. Executing a manipulation can lead to double free. This vulnerability is handled as CVE-2026-91018 . The attack can be executed remotely. There is not any exploit available.

2026-09-23 15:14 UTC
Security Advisories and Bulletins | Microsoft Learn

web:learn.microsoft.com

In this library you will find the following security documents that have been released by the Microsoft Security Response Center (MSRC). The MSRC investigates all reports of security vulnerabilities affecting Microsoft products and services, and releases these documents as part of the ongoing effort to help you manage security risks and help keep your systems protected. Please use the ...

2026-09-23 15:14 UTC
Security Update Guide - Microsoft

web:msrc.microsoft.com

The Microsoft Security Response Center (MSRC) investigates all reports of security vulnerabilities affecting Microsoft products and services, and provides the information here as part of the ongoing effort to help you manage security risks and help keep your systems protected.

2026-09-23 15:14 UTC
Microsoft Patch Tracker (September 2026): Exploit-Ranked | Senserva

web:senserva.com

Every Microsoft security patch (KB) and the CVEs it fixes, with severity, CVSS, and CISA KEV status. Cross-linked to the CVE reference.

2026-09-23 15:14 UTC
July 18, 2026—Hotpatch KB5121768 (OS Builds 26200.8893 and 26100.8893 ...

web:support.microsoft.com

This out-of-band (OOB) update for Windows 11, version 25H2 and Windows 11, version 24H2 (KB5121768) is cumulative. It includes all improvements from previous security and non-security updates, along with an additional fix . Improvements This OOB update includes the following improvement: [System Performance] This update addresses an issue affecting a limited number of devices with an Intel ...

2026-09-23 15:14 UTC
CVE-2026-91018 - lwIP Double Free Vulnerability Leads to…

web:vulmon.com

Vulnerability Summary A double free vulnerability in lwIP (Lightweight IP) may lead to system crashes, denial of service, memory corruption, or code execution on affected systems.

2026-09-23 15:14 UTC
Patch Tuesday September 2026: Security Updates & CVE Analysis

web:zecurit.com

Get the complete breakdown of Microsoft's September 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .

2026-09-23 15:14 UTC

AI Forensic Analysis

Only Available for Registered Users. Sign in to view.

Raw JSON

The full cvelistV5 record. Download as CVE-2026-91018.json.

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "lwIP API",
          "vendor": "lwIP",
          "versions": [
            {
              "lessThanOrEqual": "2.2.1",
              "status": "affected",
              "version": "2.0.1",
              "versionType": "custom"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Eric Evenchick of Tetrel Security reported this vulnerability to CISA."
        }
      ],
      "datePublic": "2026-09-22T17:53:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "lwIP (Lightweight IP)&nbsp;has a double free vulnerability, which could crash the system, cause a DoS, memory corruption, or allow code execution on the victim system."
            }
          ],
          "value": "lwIP (Lightweight IP)\u00a0has a double free vulnerability, which could crash the system, cause a DoS, memory corruption, or allow code execution on the victim system."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "ADJACENT_NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        },
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "ADJACENT",
            "baseScore": 8.7,
            "baseSeverity": "HIGH",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-415",
              "description": "CWE-415 Double free",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-22T20:25:33.530Z",
        "orgId": "7d14cffa-0d7d-4270-9dc0-52cabd5a23a6",
        "shortName": "icscert"
      },
      "references": [
        {
          "url": "https://cgit.git.savannah.gnu.org/cgit/lwip.git"
        },
        {
          "url": "https://www.cisa.gov/news-events/ics-advisories/icsa-26-265-02"
        },
        {
          "url": "https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-265-02.json"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "Users of lwIP are encouraged to update their version of lwIP using the repository found at&nbsp;<a href=\"https://cgit.git.savannah.gnu.org/cgit/lwip.git\">https://cgit.git.savannah.gnu.org/cgit/lwip.git</a>. The commit identifier that contains the fix is f873b6295933e4149a2132adf3e9a2d2a676a5ec."
            }
          ],
          "value": "Users of lwIP are encouraged to update their version of lwIP using the repository found at\u00a0 https://cgit.git.savannah.gnu.org/cgit/lwip.git . The commit identifier that contains the fix is f873b6295933e4149a2132adf3e9a2d2a676a5ec."
        }
      ],
      "source": {
        "advisory": "ICSA-26-265-02",
        "discovery": "EXTERNAL"
      },
      "title": "Double Free in lwIP (lightweight IP)",
      "x_generator": {
        "engine": "Vulnogram 1.0.5"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "7d14cffa-0d7d-4270-9dc0-52cabd5a23a6",
    "assignerShortName": "icscert",
    "cveId": "CVE-2026-91018",
    "datePublished": "2026-09-22T20:25:33.530Z",
    "dateReserved": "2026-09-14T16:40:45.500Z",
    "dateUpdated": "2026-09-22T20:25:33.530Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}