Bug 2538778 (CVE-2026-87121)

Summary: CVE-2026-87121 lwip: lwip: Arbitrary code execution via MQTT out-of-bounds write
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: urgent Docs Contact:
Priority: urgent    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in lwIP’s MQTT client. When parsing malformed MQTT fixed headers, the client can write beyond its receive buffer. A remote peer supplying crafted MQTT traffic could cause a client crash or potentially execute arbitrary code on the device. The reported affected versions are 2.0.1 through 2.2.1 inclusive.
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Description OSIDB Bzimport 2026-09-22 20:31:45 UTC
lwIP TCP/IP Stack MQTT is vulnerable to an out-of-bounds write, which may allow an attacker to gain full code execution on the device.