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Memory Buffer Bounds ErrorWeakness · CWE-119

CVE-2026-8836

CRITICAL · 9.8 CVSS v3.1 Published 2026-05-18
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A vulnerability was found in lwIP up to 2.2.1. Affected is the function snmp_parse_inbound_frame of the file src/apps/snmp/snmp_msg.c of the component snmpv3 USM Handler. Performing a manipulation of the argument msgAuthenticationParameters results in stack-based buffer overflow. The attack may be initiated remotely. The patch is named 0c957ec03054eb6c8205e9c9d1d05d90ada3898c. It is suggested to install a patch to address this issue.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A stack-based buffer overflow exists in lwIP's SNMPv3 USM handler (snmp_parse_inbound_frame function in src/apps/snmp/snmp_msg.c). The vulnerability is triggered by manipulating the msgAuthenticationParameters argument during SNMP frame parsing, allowing potential remote code execution. The issue affects all lwIP versions up to 2.2.1.

MitigationApply the patch 0c957ec03054eb6c8205e9c9d1d05d90ada3898c to fix the bounds checking issue in the SNMPv3 authentication parameters parsing. Given the critical CVSS 9.8 rating and remote attack vector, prioritize deployment.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify lwIP version
    Search for lwIP source files or libraries and check version headers (like lwipopts.h, version.h, or release notes). Common locations: /usr/include/lwip, /opt/*/lwip, or embedded firmware images.
    Affected if lwIP version is 2.2.1 or lower (or unversioned/development build)
  2. Confirm SNMP module is enabled
    Examine lwIP configuration (lwipopts.h) for #define LWIP_SNMP 1 or similar SNMP compile flags. In firmware, search for SNMP-related strings or MIB configurations.
    Affected if SNMP support is compiled into the firmware/application
  3. Verify SNMPv3 is in use
    Check configuration for SNMPv3-specific defines (like LWIP_SNMP_V3, SNMP_V3_ENABLED) or examine running configuration via SNMP GET requests for usmUserTable entries.
    Affected if SNMPv3 is enabled in the configuration or USM users are configured
  4. Check if SNMPv3 authentication parsing is active
    Monitor network traffic for SNMPv3 packets with msgAuthenticationParameters field, or review application logs for SNMP frame processing. In code, verify snmp_msg.c is linked and the snmp_parse_inbound_frame function is reachable.
    Affected if The device/application parses SNMPv3 frames with authentication parameters

Affected if lwIP version is 2.2.1 or below AND SNMPv3 with USM authentication is enabled and actively processing network requests.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Patch available Apply the vendor patch
Vendor patch github.com →
Interim mitigation

Apply the patch 0c957ec03054eb6c8205e9c9d1d05d90ada3898c to fix the bounds checking issue in the SNMPv3 authentication parameters parsing. Given the critical CVSS 9.8 rating and remote attack vector, prioritize deployment.

Recommended fix Moderate confidence
  1. 1. Navigate to the lwIP repository at https://github.com/lwip-tcpip/lwip
  2. 2. Locate the commit 0c957ec03054eb6c8205e9c9d1d05d90ada3898c in the repository history
  3. 3. Review the changes made in this commit to understand the fix for the snmp_parse_inbound_frame function in src/apps/snmp/snmp_msg.c
  4. 4. Apply the patch from commit 0c957ec03054eb6c8205e9c9d1d05d90ada3898c to your local lwIP source code
  5. 5. Rebuild the lwIP library with the patched code
  6. 6. Redeploy the updated library to all affected systems that use the SNMPv3 USM Handler functionality
  7. 7. Verify the fix does not introduce regressions by running existing SNMPv3 tests

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing12.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,760
Get the patch applied

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $7,616.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-8836 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data