CVE-2026-20777: A heap-based buffer overflow vulnerability exists in the Nicolet WFT parsing functionality of The Biosig Proje

This week

HIGH 8.1REMOTEDOWNGRADE

CVE-2026-20777 is a high-severity flaw (CVSS 8.1) affecting libbiosig. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 52%)
CISA exploited list	No
Weakness	CWE-122
Published	2026-03-03
Last modified	2026-06-17

Publisher (CNA): Talos · Vendor: libbiosig project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-03 15:16 UTCPublished CVE record published
2026-06-17 10:17 UTCUpdated Record last modified

libbiosig project libbiosig DOWNGRADE

Affected: 3.9.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.9.2

1. Check installed version

apt-cache policy libbiosig || rpm -q libbiosig || libbiosig --version

2. No fixed release: DOWNGRADE to a release before 3.9.2 (Debian / Ubuntu)

apt-cache madison libbiosig sudo apt install libbiosig=<VERSION_BEFORE_3.9.2> sudo apt-mark hold libbiosig

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list libbiosig sudo dnf downgrade libbiosig-<VERSION_BEFORE_3.9.2> sudo dnf versionlock add libbiosig

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-20777?

libbiosig: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-20777 being exploited?

CVE-2026-20777 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-20777 affect?

CVE-2026-20777 affects libbiosig. Severity is high (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. An attacker c

How urgent is CVE-2026-20777?

Priority 50/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-22891 CRITICAL 9.8 DOWNGRADE A heap-based buffer overflow vulnerability exists in the Intan CLP parsing functionality of The Biosig Project
CVE-2025-64736 MEDIUM 6.1 DOWNGRADE An out-of-bounds read vulnerability exists in the ABF parsing functionality of The Biosig Project libbiosig 3.
CVE-2025-54494 CRITICAL 9.8 UPGRADE A stack-based buffer overflow vulnerability exists in the MFER parsing functionality of The Biosig Project lib
CVE-2025-54493 CRITICAL 9.8 UPGRADE A stack-based buffer overflow vulnerability exists in the MFER parsing functionality of The Biosig Project lib
CVE-2025-54492 CRITICAL 9.8 UPGRADE A stack-based buffer overflow vulnerability exists in the MFER parsing functionality of The Biosig Project lib

References

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