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TI-2021-08270 Aliases CVE-2021-26529GHSA-h9wv-3h63-q247

The mg_tls_init function in Cesanta Mongoose HTTPS server 7.0 and 6.7-6.18 (compiled with…

Priority MEDIUM 42CWE-787Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · High · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA.

Summary

The mg_tls_init function in Cesanta Mongoose HTTPS server 7.0 and 6.7-6.18 (compiled with mbedTLS support) is vulnerable to remote OOB write attack via connection request after exhausting memory pool.

Why it matters now

EPSS 0.01509 74th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix No fix listed No fixed version in the sources yet

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
——all versions—No fix listedCNA
  • — Vendor— Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 2

CPEVersionsRoleVendor
cpe:2.3:a:cesanta:mongoose:*:*:*:*:*:*:*:*6.7 – 6.18VulnerableCesanta
cpe:2.3:a:cesanta:mongoose:7.0:*:*:*:*:*:*:*7.0VulnerableCesanta
  • cpe:2.3:a:cesanta:mongoose:*:*:*:*:*:*:*:* Versions 6.7 – 6.18 Vulnerable ·Cesanta
  • cpe:2.3:a:cesanta:mongoose:7.0:*:*:*:*:*:*:* Versions 7.0 Vulnerable ·Cesanta

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-26529
  2. 2026-10-03 Alias added: GHSA-h9wv-3h63-q247

References

Exploit 1

  • TI-2026-51393 Mongoose: Content-Length + Transfer-Encoding coexistence enables request smuggling CVSS 3.1CRITICAL 9.1
  • TI-2026-51389 Mongoose: TLS Hostname Verification Bypass via Overly Permissive Wildcard Matching CVSS 4.0CRITICAL 9.1
  • TI-2023-02723 Cesanta Mongoose MQTT Message Parsing Heap Overflow CVSS 3.1HIGH 8.8
  • TI-2020-15865 Buffer overflow in mg_resolve_from_hosts_file in Mongoose 6.18, when reading from a crafted hosts file. CVSS 3.1HIGH 8.8
  • TI-2023-17032 The HTTP server in Mongoose before 7.10 accepts requests containing negative… CVSS 3.1HIGH 7.5
  • TI-2026-06113 Cesanta Mongoose TCP Option net_builtin.c handle_opt infinite loop CVSS 4.0MEDIUM 6.9
See all 54 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences