CVE & CISA-KEV Catalog

CVE-2026-76821

HIGH
7.1
CVSS v4
NVD

Description

OpenCTI is an open source platform for managing cyber threat intelligence knowledge and observables. Prior to 7.260706.0, the JSON ingestion mapper's extractWithRegexp formula function compiled a user-supplied regular expression with the JavaScript RegExp engine in opencti-platform/opencti-graphql/src/parser/json-mapper.ts without validating its complexity. An authenticated user with JSON mapper creation permission could provide a catastrophically backtracking pattern and matching ingestion input, blocking the Node.js event loop and making the GraphQL API unavailable to all users. Scheduled ingestion could repeatedly execute the malicious mapper without additional attacker action, and recovery could require disabling the mapper and restarting the process. The issue affects availability and does not expose or modify data. This issue is fixed in version 7.260706.0.

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

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CVSS v4 Vector

Exploitability

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredLow
User InteractionNone

Impact

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/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

Exploit Intelligence

EPSS data unavailable for this CVE.

References

Related Vulnerabilities

Other CWE-400 (Resource Exhaustion) vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2023-44487High7.5100%KEVFix
CVE-2021-44228Critical10.0100%KEV + RansomFix
CVE-2011-3192High7.899%-Fix
CVE-2019-11478Medium5.395%-Fix
CVE-2023-21547High7.589%-Fix
CVE-2018-1000115High7.588%-Fix

Common questions

How do I fix CVE-2026-76821?

No published fix for CVE-2026-76821 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

How severe is CVE-2026-76821?

CVE-2026-76821 has a CVSS v4 base score of 7.1, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-16.