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9.4
CVE-2026-91018: lwIP may crash or be taken over
CVE-2026-91018 · published 21 days ago
Summary
The lightweight IP library (lwIP) can free the same memory twice, which can cause the program to stop working, become unresponsive, or let an attacker run their own code. This affects any product that includes the lwIP API. Update to the latest lwIP version or apply the vendor's patch to stop the problem.
What to do
- Update debian lwip to version 2.2.1+dfsg1-8.
Affected software
| Ecosystem | Vendor | Product | Affected versions |
|---|---|---|---|
| – | lwip | lwip api | <= 2.2.1 |
| Ubuntu:Pro:20.04:LTS | canonical | lwip | All versions |
| Debian:12 | debian | lwip | All versions |
| Debian:14 | debian | lwip |
< 2.2.1+dfsg1-8 Fix: upgrade to 2.2.1+dfsg1-8
|
Original advisory text
Double Free in lwIP (lightweight IP)
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.
References
- https://cgit.git.savannah.gnu.org/cgit/lwip.git
- https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-26...
- https://ubuntu.com/security/CVE-2026-91018 Third Party Advisory
- https://www.cve.org/CVERecord?id=CVE-2026-91018 Third Party Advisory
- https://www.cisa.gov/news-events/ics-advisories/icsa-26-265-02
- https://security-tracker.debian.org/tracker/CVE-2026-91018 Vendor Advisory
Internet-facing
14 days
Internal
At next upgrade
- Not known to be exploited
- Needs hands-on effort to exploit
- Gives an attacker full control
Severity
9.4
Critical
Type
CWE-415Double Free
Timeline
Published22 Sep 2026
Updated14 Oct 2026
First seen22 Sep 2026
Sources
CVE-2026-91018 · NVD
CVE-2026-91018 · MITRE
UBUNTU-CVE-2026-91018 · OSV
DEBIAN-CVE-2026-91018 · OSV
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