CVE-2026-6986Cesanta Mongoose GCM Authentication Tag tls_aes128.c mg_aes_gcm_decrypt signature verification
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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.
- CVSS
- 3.7 LOW (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C
- Weakness (CWE)
- CWE-347, CWE-345
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- VulDB
- NVD analysis
- Analyzed
- Record last updated
- Apr 27, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Cesanta Mongoose cesanta:mongoose | 7.0; 7.1; 7.2; 7.3; 7.4; 7.5; 7.6; 7.7; and 14 more ranges | CNA record |
cesanta mongoose cesanta:mongoose | from 7.0 before 7.21 | NVD |
References
- https://vuldb.com/vuln/359529vdb-entry, technical-description, third-party-advisory
- https://vuldb.com/vuln/359529/ctisignature, permissions-required, vdb-entry
- https://vuldb.com/submit/796231third-party-advisory, vdb-entry
- https://github.com/dwBruijn/CVEs/blob/main/Mongoose/AESGCM.mdexploit, third-party-advisory
- https://github.com/cesanta/mongoose/releases/tag/7.21patch, release-notes
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.