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CVE-2026-5244

Cesanta Mongoose buffer overflow

7.3 HIGHPublic exploitEPSS 0.76%
  1. Published2 Apr 2026

Description

A vulnerability has been found in Cesanta Mongoose up to 7.20. This affects the function mg_tls_recv_cert of the file mongoose.c of the component TLS 1.3 Handler. Such manipulation of the argument pubkey leads to heap-based buffer overflow. The attack may be launched remotely. The exploit has been disclosed to the public and may be used. Upgrading to version 7.21 mitigates this issue. The name of the patch is 0d882f1b43ff2308b7486a56a9d60cd6dba8a3f1. It is advisable to upgrade the affected component. The vendor was contacted early, responded in a very professional manner and quickly released a fixed version of the affected product.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityLow
IntegrityLow
AvailabilityLow
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Affected products

Cesanta Mongoose≥ 7.0 < 7.21

Remediation

Fixed in
Cesanta Mongoose≥ 7.21

References

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Frequently asked

Is CVE-2026-5244 being actively exploited?

CVE-2026-5244 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.76%.

How severe is CVE-2026-5244?

CVE-2026-5244 has a CVSS 3.1 base score of 7.3, rated high. EPSS estimates a 0.76% probability of exploitation.

Which products are affected by CVE-2026-5244?

Affected products include Cesanta Mongoose.

How do I fix CVE-2026-5244?

Upgrade affected software to a fixed version, for example Cesanta Mongoose 7.21 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-5244 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.