CVE-2026-8836Network attack vector

Remote memory corruption via unchecked SNMPv3 parameter length

Published May 18, 2026 · Updated May 18, 2026

Stack-based buffer overflow in lwIP 2.1.0 through 2.2.1 allows remote attackers to corrupt memory via a crafted SNMPv3 packet. The snmp_parse_inbound_frame function treats the untrusted msgAuthenticationParameters length as both the copy length and destination bound, allowing snmp_asn1_dec_raw to overrun a fixed-size stack buffer. Exposure requires the optional SNMPv3 agent to process the malformed packet; the overflow can crash the embedded service or corrupt control data without authentication or user interaction.

CVSS severity9.8
Critical
EPSS probability1.10%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in lwIP 2.1.0 through 2.2.1 allows remote attackers to corrupt memory via a crafted SNMPv3 packet. The snmp_parse_inbound_frame function treats the untrusted msgAuthenticationParameters length as both the copy length and destination bound, allowing snmp_asn1_dec_raw to overrun a fixed-size stack buffer. Exposure requires the optional SNMPv3 agent to process the malformed packet; the overflow can crash the embedded service or corrupt control data without authentication or user interaction.

The record

CVE
CVE-2026-8836
Published
May 18, 2026
Updated
May 18, 2026
Vendor
lwIP
Product
lwIP
Classifications
CWE-121, CWE-119, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 18, 2026CVE publishedPublication date reported by the CVE source.
  2. May 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.1.0
  2. Affected versionversion=2.1.1
  3. Affected versionversion=2.1.2
  4. Affected versionversion=2.1.3
  5. Affected versionversion=2.2.0
  6. Affected versionversion=2.2.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

lwIP · lwIPversion=2.1.0; version=2.1.1; version=2.1.2; version=2.1.3; version=2.2.0; version=2.2.1

Published CVSS scores

9.8VulDBCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
10.0VulDBAV:N/AC:L/Au:N/C:C/I:C/A:C
8.9VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow
CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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