What is the CVSS score of CVE-2026-20777?

CVE-2026-20777 has a CVSS 3.1 base score of 8.1 (High). CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.1%.

Is there a public PoC exploit available for CVE-2026-20777?

Yes, a public proof-of-concept exploit is available for CVE-2026-20777. Prioritise patching immediately. EPSS: 0.1%.

How to fix or mitigate CVE-2026-20777?

Within 24 hours: Identify all systems and applications using libbiosig 3.9.2 or the Master Branch; disable .wft file upload/processing capabilities if possible and implement input validation. Within 7 days: Isolate affected systems from critical networks; restrict file uploads to trusted sources only; implement application whitelisting and file type validation at network boundaries. Within 30 days: Contact vendor for patch availability; evaluate alternative biosignal libraries; develop and test migration plan; coordinate with Biosig Project for security updates.

Libbiosig CVE-2026-20777

HIGH

Heap-based Buffer Overflow (CWE-122)

2026-03-03 talos-cna@cisco.com

Buffer Overflow Heap Overflow Libbiosig Libbiosig Project

8.1

CVSS 3.1 · NVD

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Craft malicious .wft file with oversized header
Exploit

Victim opens file in libbiosig parser
Execution

Heap buffer overflow during WFT parsing
Impact

Execute arbitrary code with parser privileges

Vulnerability Assessment

Weakness	CWE CWE-122 OWASP Top 10:2025 A06:2021 - Vulnerable and Outdated Components ASVS 5.0 V15 - Secure Coding and Architecture Heap buffer bounds checking MITRE ATT&CK 1 technique across 1 tactic: Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Exploitation Conditions	libbiosig version 3.9.2 or Master Branch with WFT file parsing enabled. Attacker must supply malicious .wft file to target. AC:H indicates non-trivial crafting required to trigger overflow reliably.
Impact	CVSS 8.1 (HIGH). Attack vector: Network. Complexity: High. Privileges required: None. User interaction: None. Public exploit/POC available.
Exploit ScenarioDerived	An attacker could exploit this vulnerability to arbitrary code execution.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Arbitrary code execution in libbiosig 3.9.2 and Master Branch can be triggered by parsing malicious Nicolet WFT files through a heap buffer overflow in the WFT parsing functionality. An attacker can exploit this vulnerability by supplying a crafted .wft file to execute arbitrary code on affected systems. Public exploit code exists for this vulnerability, though no patch is currently available.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 22:05 CVSS 8.1

A heap-based buffer overflow vulnerability exists in the Nicolet WFT parsing functionality of The Biosig Project libbiosig 3.9.2 and Master Branch (db9a9a63). A specially crafted .wft file can lead to arbitrary code execution. [CVSS 8.1 HIGH]

RemediationAI

Monitor vendor advisories for a patch. Enable ASLR, DEP/NX, and stack canaries where possible. Restrict network access to the affected service where possible.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Classified as CWE-122 (Heap-based Buffer Overflow). Affects the Nicolet WFT parsing component of Libbiosig. A heap-based buffer overflow vulnerability exists in the Nicolet WFT parsing functionality of The Biosig Project libbiosig 3.9.2 and Master Branch (db9a9a63). A specially crafted .wft file can lead to arbitrary code execution. An attacker can provide a malicious file to trigger this vulnerability.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.1 HIGH

AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

PoC Detected

Mar 05, 2026 - 18:16 vuln.today

Public exploit code

CVE Published

Mar 03, 2026 - 15:16 nvd

HIGH 8.1

DescriptionCVE.org

Executive ViewAI

Why It Matters

A critical heap-based buffer overflow in libbiosig 3.9.2 allows attackers to execute arbitrary code by processing malicious .wft files. Any organization using biosignal processing tools built on this library faces immediate risk of system compromise, data theft, and operational disruption. This vulnerability is particularly dangerous because public exploits already exist and no patch is currently available.

Business Impact: High

Compensating Controls

Disable .wft file parsing functionality in affected applications; implement strict file upload controls (whitelist only approved .wft files); deploy network segmentation to isolate systems processing WFT files; use Web Application Firewall (WAF) rules to block suspicious file uploads; enforce endpoint detection and response (EDR) monitoring on systems handling biosignal data; require manual verification of .wft file sources; implement application sandboxing for file processing.

Threat Intelligence Overview

EPSS Score

0.1%

Top 69% exploitable

Exploit

POC

Public exploit code exists

Data Quality

3 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC Yes

EPSS 0.1%

Patch available Yes

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

Poc

System Exposure· derived

Open

Automatable· derived

Human Impact

High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +40

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Buffer Overflow HIGH

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Heap Overflow HIGH

A heap overflow occurs when a program writes data beyond the bounds of a buffer allocated in the heap memory region.