CVE-2026-6986: Improper Verification of Cryptographic Signature in Cesanta Mongoose
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.
AI Analysis
Technical Summary
This vulnerability in Cesanta Mongoose (versions up to 7.20) stems from improper verification of cryptographic signatures within the mg_aes_gcm_decrypt function of the GCM Authentication Tag Handler component. This weakness could allow an attacker to bypass cryptographic authentication remotely, although the attack requires high complexity and no privileges or user interaction. The vendor has confirmed that the issue is fixed in version 7.21.
Potential Impact
The vulnerability allows remote attackers to potentially bypass cryptographic signature verification, which could undermine data integrity or authentication mechanisms relying on AES-GCM. However, the attack complexity is high, and no known exploits are currently observed in the wild, limiting immediate risk.
Mitigation Recommendations
A fixed version (7.21) is available and upgrading to this version is strongly recommended. The vendor has confirmed the issue is resolved in this release. No additional mitigation steps are indicated by the vendor advisory.
CVE-2026-6986: Improper Verification of Cryptographic Signature in Cesanta Mongoose
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.
CVSS v4.0
Score 6.3medium
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability in Cesanta Mongoose (versions up to 7.20) stems from improper verification of cryptographic signatures within the mg_aes_gcm_decrypt function of the GCM Authentication Tag Handler component. This weakness could allow an attacker to bypass cryptographic authentication remotely, although the attack requires high complexity and no privileges or user interaction. The vendor has confirmed that the issue is fixed in version 7.21.
Potential Impact
The vulnerability allows remote attackers to potentially bypass cryptographic signature verification, which could undermine data integrity or authentication mechanisms relying on AES-GCM. However, the attack complexity is high, and no known exploits are currently observed in the wild, limiting immediate risk.
Mitigation Recommendations
A fixed version (7.21) is available and upgrading to this version is strongly recommended. The vendor has confirmed the issue is resolved in this release. No additional mitigation steps are indicated by the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulDB
- Date Reserved
- 2026-04-24T19:12:51.609Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
- Epss Score
- 0.00015
- Epss Percentile
- 0.0298
- Epss Date
- 2026-04-26
- Gcve Source
- db.gcve.eu
Threat ID: 69ecf11887115cfb681e8335
Added to database: 4/25/2026, 4:51:36 PM
Last enriched: 5/3/2026, 7:25:03 AM
Last updated: 6/9/2026, 9:56:03 PM
Views: 70
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