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[USN-8423-1] lwIP vulnerabilities

Posted on 11 June 2026
Ubuntu Security

==========================================================================Ubuntu Security Notice USN-8423-1
June 11, 2026

lwip vulnerabilities
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 26.04 LTS
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS

Summary:

Several security issues were fixed in lwIP.

Software Description:
- lwip: Lightweight TCP/IP stack

Details:

It was discovered that lwIP contained a buffer overflow in the EAP
authentication handling code. An attacker could possibly use this issue
to trigger a buffer overflow, resulting in arbitrary code execution or a
denial of service. This issue only affected Ubuntu 20.04 LTS.
(CVE-2020-8597)

It was discovered that lwIP incorrectly handled certain ICMPv6 or
6LoWPAN packets. An attacker could possibly use this issue to trigger a
buffer overflow, resulting in information disclosure. This issue only
affected Ubuntu 20.04 LTS. (CVE-2020-22283, CVE-2020-22284)

It was discovered that lwIP did not properly validate certain SNMPv3
authentication parameters. An attacker could possibly use this issue to
trigger a stack-based buffer overflow, resulting in arbitrary code
execution or a denial of service. (CVE-2026-8836)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 26.04 LTS
liblwip-dev 2.2.1+dfsg1-4ubuntu0.1~esm1
Available with Ubuntu Pro
liblwip-doc 2.2.1+dfsg1-4ubuntu0.1~esm1
Available with Ubuntu Pro
liblwip0t64 2.2.1+dfsg1-4ubuntu0.1~esm1
Available with Ubuntu Pro

Ubuntu 24.04 LTS
liblwip-dev 2.2.0+dfsg1-6.1ubuntu0.1~esm1
Available with Ubuntu Pro
liblwip-doc 2.2.0+dfsg1-6.1ubuntu0.1~esm1
Available with Ubuntu Pro
liblwip0t64 2.2.0+dfsg1-6.1ubuntu0.1~esm1
Available with Ubuntu Pro

Ubuntu 22.04 LTS
liblwip-dev 2.1.3+dfsg1-1ubuntu0.1~esm1
Available with Ubuntu Pro
liblwip-doc 2.1.3+dfsg1-1ubuntu0.1~esm1
Available with Ubuntu Pro
liblwip0 2.1.3+dfsg1-1ubuntu0.1~esm1
Available with Ubuntu Pro

Ubuntu 20.04 LTS
liblwip-dev 2.1.2+dfsg1-4ubuntu0.1~esm1
Available with Ubuntu Pro
liblwip-doc 2.1.2+dfsg1-4ubuntu0.1~esm1
Available with Ubuntu Pro
liblwip0 2.1.2+dfsg1-4ubuntu0.1~esm1
Available with Ubuntu Pro

In general, a standard system update will make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-8423-1
CVE-2020-22283, CVE-2020-22284, CVE-2020-8597, CVE-2026-8836

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