Cesanta Mongoose up to 7.20 GCM Authentication Tag /src/tls_aes128.c mg_aes_gcm_decrypt signature verification

Summaryinfo

A vulnerability identified as problematic has been detected in Cesanta Mongoose up to 7.20. Impacted is the function mg_aes_gcm_decrypt of the file /src/tls_aes128.c of the component GCM Authentication Tag Handler. Performing a manipulation results in signature verification. This vulnerability is cataloged as CVE-2026-6986. It is possible to initiate the attack remotely. Furthermore, there is an exploit available. You should upgrade the affected component. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.

Detailsinfo

A vulnerability was found in Cesanta Mongoose up to 7.20. It has been classified as problematic. This affects the function mg_aes_gcm_decrypt of the file /src/tls_aes128.c of the component GCM Authentication Tag Handler. The manipulation with an unknown input leads to a signature verification vulnerability. CWE is classifying the issue as CWE-347. The product does not verify, or incorrectly verifies, the cryptographic signature for data. This is going to have an impact on integrity.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-6986. The exploitability is told to be difficult. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details and a public exploit are known.

The exploit is shared for download at github.com. It is declared as proof-of-concept. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.

Upgrading to version 7.21 eliminates this vulnerability. The upgrade is hosted for download at github.com.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• Cesanta

Name

• Mongoose

Version

• 7.0
• 7.1
• 7.2
• 7.3
• 7.4
• 7.5
• 7.6
• 7.7
• 7.8
• 7.9
• 7.10
• 7.11
• 7.12
• 7.13
• 7.14
• 7.15
• 7.16
• 7.17
• 7.18
• 7.19
• 7.20

License

• open-source

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 3.7
VulDB Meta Temp Score: 3.4

VulDB Base Score: 3.7
VulDB Temp Score: 3.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Signature verification
CWE: CWE-347 / CWE-345
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Access: Public
Status: Proof-of-Concept
Download: 🔒
Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Mongoose 7.21

Timelineinfo

04/24/2026 Advisory disclosed
04/24/2026 +0 days VulDB entry created
04/24/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-6986 (🔒)
GCVE (CVE): GCVE-0-2026-6986
GCVE (VulDB): GCVE-100-359529
scip Labs: https://www.scip.ch/en/?labs.20161013

Entryinfo

Created: 04/24/2026 21:18
Changes: 04/24/2026 21:18 (60)
Complete: 🔍
Submitter: dwbruijn
Cache ID: 216::103

Submitinfo

Accepted

• Submit #796231: Cesanta Mongoose 7.20 Improper Verification of Cryptographic Signature (by dwbruijn)

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion

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