Cesanta Mongoose GCM Authentication Tag tls_aes128.c mg_aes_gcm_decrypt signature verification

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Summary

CVECVE-2026-6986
StatePUBLISHED
AssignerVulDB
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-25 17:16:33 UTC
Updated2026-04-25 17:16:33 UTC
DescriptionA 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.

Risk And Classification

Primary CVSS: v4.0 6.3 MEDIUM from [email protected]

CVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Problem Types: CWE-345 | CWE-347 | CWE-347 Improper Verification of Cryptographic Signature | CWE-345 Insufficient Verification of Data Authenticity

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary6.3MEDIUMCVSS: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/C...
4.0CNADECLARED6.3MEDIUMCVSS: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
3.1[email protected]Primary3.7LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
3.1CNADECLARED3.7LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C
3.0CNADECLARED3.7LOWCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C
2.0[email protected]Secondary2.6AV:N/AC:H/Au:N/C:N/I:P/A:N
2.0CNADECLARED2.6AV:N/AC:H/Au:N/C:N/I:P/A:N/E:POC/RL:OF/RC:C

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
High
Attack Requirements
None
Privileges Required
None
User Interaction
None
Confidentiality
None
Integrity
Low
Availability
None
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

CVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS v3.0 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Cesanta Mongoose affected 7.0 Not specified
CNA Cesanta Mongoose affected 7.1 Not specified
CNA Cesanta Mongoose affected 7.2 Not specified
CNA Cesanta Mongoose affected 7.3 Not specified
CNA Cesanta Mongoose affected 7.4 Not specified
CNA Cesanta Mongoose affected 7.5 Not specified
CNA Cesanta Mongoose affected 7.6 Not specified
CNA Cesanta Mongoose affected 7.7 Not specified
CNA Cesanta Mongoose affected 7.8 Not specified
CNA Cesanta Mongoose affected 7.9 Not specified
CNA Cesanta Mongoose affected 7.10 Not specified
CNA Cesanta Mongoose affected 7.11 Not specified
CNA Cesanta Mongoose affected 7.12 Not specified
CNA Cesanta Mongoose affected 7.13 Not specified
CNA Cesanta Mongoose affected 7.14 Not specified
CNA Cesanta Mongoose affected 7.15 Not specified
CNA Cesanta Mongoose affected 7.16 Not specified
CNA Cesanta Mongoose affected 7.17 Not specified
CNA Cesanta Mongoose affected 7.18 Not specified
CNA Cesanta Mongoose affected 7.19 Not specified
CNA Cesanta Mongoose affected 7.20 Not specified
CNA Cesanta Mongoose unaffected 7.21 Not specified

References

ReferenceSourceLinkTags
vuldb.com/vuln/359529 [email protected] vuldb.com
github.com/cesanta/mongoose/releases/tag/7.21 [email protected] github.com
vuldb.com/submit/796231 [email protected] vuldb.com
vuldb.com/vuln/359529/cti [email protected] vuldb.com
github.com/dwBruijn/CVEs/blob/main/Mongoose/AESGCM.md [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: dwbruijn (VulDB User) (en)

CNA: VulDB CNA Team (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-04-24T00:00:00.000ZAdvisory disclosed
CNA2026-04-24T02:00:00.000ZVulDB entry created
CNA2026-04-24T21:18:01.000ZVulDB entry last update
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