MISP CurlClient TLS Peer Verification Disabled by Default Enables Man-in-the-Middle Attacks

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-85221
StatePUBLISHED
AssignerCIRCL
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-03 15:17:41 UTC
Updated2026-09-03 16:45:08 UTC
DescriptionMISP contains an improper TLS certificate validation vulnerability in CurlClient. The CurlClient::$verifyPeer property was not explicitly initialized and therefore defaulted to null. When passed to cURL, this value effectively disabled TLS peer verification unless the calling code explicitly enabled it. As a result, HTTPS connections made through affected CurlClient instances could accept certificates that were not issued by a trusted certificate authority. An attacker capable of intercepting or manipulating network traffic between a MISP instance and a remote HTTPS service could impersonate the remote endpoint and perform a man-in-the-middle attack. Successful exploitation could allow an attacker to observe sensitive information transmitted by MISP, including authentication material or exchanged threat intelligence, and to modify responses returned to the MISP instance. The impact depends on the functionality using CurlClient and the data exchanged with the remote service. The patch enables TLS peer verification by default while preserving explicit support for configured self-signed certificates. It also corrects the self-signed certificate handling in SyncTool so that peer verification is disabled only when no pinned CA certificate is configured.

Risk And Classification

Primary CVSS: v4.0 7.6 HIGH from 5a6e4751-2f3f-4070-9419-94fb35b644e8

CVSS:4.0/AV:A/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/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-295 | CWE-295 CWE-295 Improper Certificate Validation

VersionSourceTypeScoreSeverityVector
4.05a6e4751-2f3f-4070-9419-94fb35b644e8Secondary7.6HIGHCVSS:4.0/AV:A/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/C...
4.0CNACVSS7.6HIGHCVSS:4.0/AV:A/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

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

CVSS:4.0/AV:A/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Misp Misp affected 2.5.45 semver Not specified

References

ReferenceSourceLinkTags
github.com/MISP/MISP/commit/e06f69858 5a6e4751-2f3f-4070-9419-94fb35b644e8 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: Andras Iklody (en)

CNA: Claude Opus 5 (1M context) (en)

CNA: elhoim (David André) (en)

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