CVE-2026-2967 Details
Description
A security vulnerability has been detected in Cesanta Mongoose up to 7.20. This affects the function getpeer of the file /src/net_builtin.c of the component TCP Sequence Number Handler. The manipulation leads to improper verification of source of a communication channel. The attack may be initiated remotely. The attack's complexity is rated as high. The exploitability is reported as difficult. The exploit has been disclosed publicly and may be used. The vendor was contacted early about this disclosure but did not respond in any way.
A vulnerability in Cesanta Mongoose versions through 7.20 allows for blind TCP RST injection, disrupting active connections. The issue arises in the built-in TCP/IP stack (MIP), specifically within the `getpeer` function of `/src/net_builtin.c`. This function improperly verifies the source IP of incoming TCP segments, matching them to existing connections based solely on port numbers. As a result, an attacker can send a forged RST packet, terminating a connection without detection. This exploitation violates RFC 5961, enabling any host on the local network to disrupt TCP sessions by sending a single crafted packet with the correct port pair and arbitrary source IP or sequence number.
Metrics
CVSS 4.0 Severity and Vector Strings:
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Feb 23, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/dwBruijn/CVEs/blob/main/Mongoose/tcp_rst.md | [email protected] | ExploitThird Party Advisory |
| https://github.com/dwBruijn/CVEs/blob/main/Mongoose/tcp_rst.md#poc | [email protected] | ExploitThird Party Advisory |
| https://vuldb.com/?ctiid.347334 | [email protected] | Permissions RequiredVDB Entry |
| https://vuldb.com/?id.347334 | [email protected] | Third Party AdvisoryVDB Entry |
| https://vuldb.com/?submit.755450 | [email protected] | Third Party AdvisoryVDB Entry |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-940 | Improper Verification of Source of a Communication Channel | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| cesanta mongoose | <= 7.20 |
CPE
Remediation
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Change History
5 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Apr 29, 2026 | Data Remediation | [email protected] |
| Feb 23, 2026 | Initial Analysis | [email protected] |
| Feb 23, 2026 | New CVE Received | [email protected] |