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Fencer Intel
critical 9.1

CVE-2026-85221 json

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

published 2mo ago modified 2mo ago also EUVD-2026-70494

cvss
9.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 20%
public exploits
0
none known

Summary

MISP 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.

Patch / fix

  • misp-project misp 2.5.46

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
2mo ago

Exploit prediction

0.27% chance of exploitation in the next 30 days, higher than 20% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 4.0 7.6 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
CNA 4.0 7.6 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
NVD 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

  • misp misp

Classification

Weakness
  • CWE-295 Improper Certificate Validation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.