Home

Description

A security vulnerability has been detected in Cesanta Mongoose up to 7.20. This issue affects the function mg_aes_gcm_decrypt of the file /src/tls_aes128.c of the component GCM Authentication Tag Handler. Such manipulation leads to improper verification of cryptographic signature. The attack may be performed from remote. A high complexity level is associated with this attack. The exploitability is assessed as difficult. The exploit has been disclosed publicly and may be used. Upgrading to version 7.21 is capable of addressing this issue. It is advisable to upgrade the affected component. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.

PUBLISHED Reserved 2026-04-24 | Published 2026-04-25 | Updated 2026-04-27 | Assigner VulDB




MEDIUM: 6.3CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
LOW: 3.7CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C
LOW: 3.7CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C
2.6AV:N/AC:H/Au:N/C:N/I:P/A:N/E:POC/RL:OF/RC:C

Problem types

Improper Verification of Cryptographic Signature

Insufficient Verification of Data Authenticity

Product status

7.0
affected

7.1
affected

7.2
affected

7.3
affected

7.4
affected

7.5
affected

7.6
affected

7.7
affected

7.8
affected

7.9
affected

7.10
affected

7.11
affected

7.12
affected

7.13
affected

7.14
affected

7.15
affected

7.16
affected

7.17
affected

7.18
affected

7.19
affected

7.20
affected

7.21
unaffected

Timeline

2026-04-24:Advisory disclosed
2026-04-24:VulDB entry created
2026-04-24:VulDB entry last update

Credits

dwbruijn (VulDB User) reporter

VulDB CNA Team coordinator

References

vuldb.com/vuln/359529 (VDB-359529 | Cesanta Mongoose GCM Authentication Tag tls_aes128.c mg_aes_gcm_decrypt signature verification) vdb-entry technical-description

vuldb.com/vuln/359529/cti (VDB-359529 | CTI Indicators (IOB, IOC, IOA)) signature permissions-required

vuldb.com/submit/796231 (Submit #796231 | Cesanta Mongoose 7.20 Improper Verification of Cryptographic Signature) third-party-advisory

github.com/dwBruijn/CVEs/blob/main/Mongoose/AESGCM.md exploit

github.com/cesanta/mongoose/releases/tag/7.21 patch

cve.org (CVE-2026-6986)

nvd.nist.gov (CVE-2026-6986)

Download JSON