CVE-2026-73252

Status: DeferredHigh (7.5)—

Severity7.5High · CVSS 3.1

Exploitation probability0.38 %higher than 30% of CVEs

Active exploitationNonot in the CISA catalog

Public exploitNot knownno public code found

Mongoose is an embedded web server and network library. Prior to 7.23, the built-in TLS stack selected by MG_TLS_BUILTIN in src/tls_builtin.c accepts a TLS 1.3 record whose decrypted size is exactly the 16-byte authentication tag with no plaintext or ContentType byte. In mg_tls_recv_record(), the msgsz length check permits that record and the recv_len calculation underflows to SIZE_MAX, so a later handshake step treats stale buffer contents as a trusted message with an effectively unbounded length. An unauthenticated malicious TLS peer can trigger a heap out-of-bounds read before certificate or Finished validation, causing a remote denial of service. This issue is fixed in version 7.23.

CVSS

Base score: 7.5
Version: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.38 %
Percentile among all scored CVEs: 30
Score date: 10/20/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

ExploitationT1190 Exploit Public-Facing Applicationinitial access90 %
Primary impactT1499 Endpoint Denial of Serviceimpact85 %

Vector AV:N/PR:N/UI:N: un par TLS malicioso sin autenticación provoca una lectura fuera de límites en heap y denegación de servicio remota (A:H).

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

ATT&CK mitigations that cover these techniques

Filter Network Traffic Vulnerability Scanning Privileged Account Management Network Segmentation Limit Access to Resource Over Network Application Isolation and Sandboxing

Affected technologies (1)

⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.

Cesanta — Mongoose^AI

CWEs

CWE-125, CWE-191

References

Show 4 references

Raw JSON (NVD)

Show

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  "id": "CVE-2026-73252",
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          "version": "2.0.3",
          "timestamp": "2026-10-14T19:41:34.958467Z"
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  "lastModified": "2026-10-16T20:04:29.760",
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