Security Flaw in Cesanta Mongoose TCP Sequence Number Handler Affects Remote Communications
CVE-2026-2967

6.3MEDIUM

Key Information:

Vendor

Cesanta

Status
Mongoose
Vendor
CVE Published:
23 February 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-2967?

A significant security flaw exists in Cesanta Mongoose versions up to 7.20, identified within the getpeer function of the TCP Sequence Number Handler. This vulnerability allows for improper verification of the source of communication channels, potentially enabling remote attackers to exploit the flaw. Although the difficulty in executing the exploit is reportedly high, the fact that it has been disclosed publicly raises concerns about its usage in the wild. Early notification attempts to the vendor did not elicit a response, underlining the need for immediate attention from users of affected versions.

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Affected Version(s)

Mongoose 7.0

Mongoose 7.1

Mongoose 7.2

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-2967 - Proof of Concept

References

https://vuldb.com/?id.347334
vdb-entrytechnical-description
https://vuldb.com/?ctiid.347334
signaturepermissions-required
https://vuldb.com/?submit.755450
third-party-advisory

CVSS V4

Score:
6.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
Low
Attack Vector:
Network
Attack Complexity:
High
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

dwbruijn (VulDB User)
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