Is CVE-2026-73260 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-73260 being exploited in the wild.

How severe is CVE-2026-73260?

High severity, with a CVSS score of 7.5, published 14 October 2026.

Is there a fix for CVE-2026-73260?

Yes: fixed in 7.23. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Am I affected by CVE-2026-73260?

Check whether you run Cesanta Mongoose at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-73260: Mongoose TLS certificate parser bounds check in DER parsing

CVE-2026-73260 · Severity: high · CVSS 7.5 · Published 2026-10-14

Mongoose is an embedded web server and network library used in IoT and embedded systems. Prior to version 7.23, its built-in TLS certificate parser has a bounds checking flaw that allows an attacker to cause an out-of-bounds memory read and crash the server during the TLS handshake. An unauthenticated malicious TLS server, or any peer presenting a crafted certificate, can exploit this to cause a denial of service.

Technologies: Cesanta Mongoose. Vendors: Cesanta.

Quick answers

Is CVE-2026-73260 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-73260 being exploited in the wild.
How severe is CVE-2026-73260?: High severity, with a CVSS score of 7.5, published 14 October 2026.
Which products and versions are affected?: Cesanta Mongoose before 7.23.
Is there a fix for CVE-2026-73260?: Yes: fixed in 7.23. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-73260 attacked?: It is in a software library.
Am I affected by CVE-2026-73260?: Check whether you run Cesanta Mongoose at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: 7.23

Technical details

The vulnerability exists in mg_der_to_tlv() and mg_der_next() functions within the TLS certificate parser when MG_TLS_BUILTIN is selected. When parsing long-form DER element lengths, the parser fails to validate that the specified length fits within the remaining certificate buffer, allowing a peer-controlled length value to underflow a uint32_t and cause the parser to advance beyond valid memory boundaries during certificate parsing. An unauthenticated attacker can send a malicious TLS server response or client certificate to trigger an out-of-bounds read and denial of service.

Affected products

Cesanta Mongoose before 7.23

Timeline

2026-10-14: disclosed
2026-08-12: patched: Version 7.23 released

References

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