Cesanta Mongoose TCP Option net_builtin.c handle_opt infinite loop

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Summary

CVECVE-2026-6985
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 weakness has been identified in Cesanta Mongoose up to 7.20. This vulnerability affects the function handle_opt of the file /src/net_builtin.c of the component TCP Option Handler. This manipulation of the argument optlen causes infinite loop. The attack is possible to be carried out remotely. The exploit has been made available to the public and could be used for attacks. Upgrading to version 7.21 is able to resolve this issue. Upgrading the affected component is advised. VulDB has contacted the vendor early and they confirmed quickly, that this issue got fixed already.

Risk And Classification

Primary CVSS: v4.0 5.5 MEDIUM from [email protected]

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/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-404 | CWE-835 | CWE-835 Infinite Loop | CWE-404 Denial of Service

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary5.5MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/C...
4.0CNADECLARED6.9MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
3.1[email protected]Primary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
3.1CNADECLARED5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C
3.0CNADECLARED5.3MEDIUMCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C
2.0[email protected]Secondary5AV:N/AC:L/Au:N/C:N/I:N/A:P
2.0CNADECLARED5AV:N/AC:L/Au:N/C:N/I:N/A:P/E:POC/RL:OF/RC:C

CVSS v4.0 Breakdown

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

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/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
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

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

CVSS v3.0 Breakdown

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

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/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
github.com/dwBruijn/CVEs/blob/main/Mongoose/TCP_opt_dos.md [email protected] github.com
github.com/cesanta/mongoose/releases/tag/7.21 [email protected] github.com
vuldb.com/submit/796230 [email protected] vuldb.com
vuldb.com/vuln/359528 [email protected] vuldb.com
vuldb.com/vuln/359528/cti [email protected] vuldb.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
CNA2026-04-24T21:17:57.000ZVulDB entry last update
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