CVE-2026-91018: Double Free in lwIP (lightweight IP)

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-22 · updated 2026-09-23
Weakness: CWE-415

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.

Affected products

lwIP API: from 2.0.1 through 2.2.1

References

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

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