Out-of-bounds write in lwIP TCP/IP Stack MQTT Client Application
Priority MEDIUM 49CWE-787Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- No fix listed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-787 and the CVSS impact.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00775 56th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2026-87121
- 2026-10-03 Alias added: GHSA-h8q6-7rjx-3m2r
- 2026-10-09 Affected versions changed · Red Hat
- 2026-10-09 CVSS score added · Red Hat
- 2026-10-25 EPSS moved to the 50th–90th percentile
References
More lwIP vulnerabilities
- TI-2026-76190 Stack out-of-bounds write in lwIP mDNS response handler CVSS 4.0MEDIUM 6.0
- TI-2026-61856 Double Free in lwIP (lightweight IP) CVSS 4.0HIGH 8.7
- TI-2026-82411 Out-of-bounds read in lwIP SNMP agent leaks adjacent memory CVSS 4.0MEDIUM 6.9
Sources
- CVE-2026-87121 · CVE Program
- CVE-2026-87121 · NVD
- FIRST EPSS
- GHSA-h8q6-7rjx-3m2r · GitHub Advisory Database · CC BY 4.0
- CVE-2026-87121 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences