---
title: "RACK stack - Out-of-Bounds Write"
description: "The RACK stack contains an out-of-bounds write caused by repeated doubling of a 16-bit allocation counter that wraps to zero during PCM sample array expansion, letting remote attackers cause kernel panic by sending many ACKs on an established TCP connection."
url: https://panop.io/threat-heartbeat/CVE-2026-101307/
---

# CVE-2026-101307 RACK stack - Out-of-Bounds Write

The RACK stack contains an out-of-bounds write caused by repeated doubling of a 16-bit allocation counter that wraps to zero during PCM sample array expansion, letting remote attackers cause kernel panic by sending many ACKs on an established TCP connection.

CVSS base score 8.2 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.17% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-101307)

## Details

Type

Out Of Bounds Rw

Impact

Denial Of Service

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/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

Published

15 October 2026

Updated

16 October 2026

Weakness

[CWE-122](https://cwe.mitre.org/data/definitions/122.html)

## Vendor fix

Update to the latest version with the fix for the allocation counter wrap issue.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-101307](https://nvd.nist.gov/vuln/detail/CVE-2026-101307)
- [https://security.freebsd.org/advisories/FreeBSD-SA-26:70.tcp.asc](https://security.freebsd.org/advisories/FreeBSD-SA-26:70.tcp.asc)

[← All CVEs](https://panop.io/threat-heartbeat/)

## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

[Book a demo](https://panop.io/demo)