Security Resilience

CVE-2026-78861

Published
05 October 2026
Modified
06 October 2026
CVSS Score v3.1 7.7
Click a component to see what it means
Raw vectorCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS Score 0.0014 3th percentile
Risk Priority 55 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-78861 is a high-severity Memory Allocation with Excessive Size Value (CWE-789) vulnerability in Gitbook (inferred from references). Its CVSS base score is 7.7 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Endpoint Denial of Service (T1499); ranked at the 3th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SC-6 (Resource Availability) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

An issue in Mercusys AC12 V2 allows a local attacker to execute arbitrary code via a hardcoded 512-bit RSA Private Key

CWE(s)
CWE-789

Related Threats

MITRE ATT&CK Enterprise Techniques

T1499 Endpoint Denial of Service Impact
Adversaries may perform Endpoint Denial of Service (DoS) attacks to degrade or block the availability of services to users.
attack.mitre.org →
T1499.003 Application Exhaustion Flood Impact
Adversaries may target resource intensive features of applications to cause a denial of service (DoS), denying availability to those applications.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-26931Shared CWE-789
CVE-2023-30837Shared CWE-789
CVE-2026-25780Shared CWE-789
CVE-2025-29491Shared CWE-789
CVE-2026-40378Shared CWE-789
CVE-2021-47971Shared CWE-789
CVE-2025-2518Shared CWE-789
CVE-2025-12983Shared CWE-789
CVE-2026-44967Shared CWE-789
CVE-2026-102466Shared CWE-789

Affected Assets

Gitbook
—
inferred from references and description; NVD did not file a CPE for this CVE

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SC-6 Resource Availability partial match

Resource quotas and priority allocation limit the system-wide impact of an oversized request.

SI-10 Information Input Validation partial match

Input validation directly rejects or bounds untrusted size values before any allocation occurs.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
blocks

Secure SDLC practices directly prevent coding flaws that trust unvalidated size values for allocations.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development can detect and block excessive allocation flaws before deployment.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly prohibit allocating memory from untrusted size values without validation.

References