CVE-2026-101307: Remotely triggerable buffer overflow in tcp_rack

High 8.2 EPSS 0.3% FreeBSD

When the PCM sample array needs to grow, the RACK stack doubles a 16-bit allocation counter. Repeated doublings caused the counter to wrap to zero, resulting in a near-zero-length allocation followed by a copy of the existing samples into the undersized buffer. A remote peer can trigger the expansion by sending a sufficient number of ACKs on an established connection. A remote attacker who can establish a TCP connection to a system using the RACK stack can trigger an out-of-bounds write of approximately 512 KB in the kernel heap possibly resulting in a kernel panic.

CVE-2026-101307CVE identifier
8.2CVSS 4.0 base score (high)
0.3%EPSS: chance of exploitation in the next 30 days (higher than 24% of CVEs)
2026-10-15published

What do these terms mean? CVE · CVSS score · exploited (KEV) · EPSS · backported fix · all terms

What to do now

Check whether you run FreeBSD and which version (commands below).
Install the fixed version for your system: see “Patch it” below.
Reboot when the advisory touches the kernel or core libraries; otherwise restart the affected daemons (the advisory says which)

Affected and fixed versions

Affected:

FreeBSD FreeBSD 15.1-RELEASE to before p5

Patch it

Use the commands for your system. Distribution packages often keep an older version number with the fix backported, so compare with the fixed package versions in the table below, not only with the upstream version.

FreeBSD

base system: freebsd-update fetch install; packages: pkg upgrade

General update steps for every system are on the Linux and Unix & BSD pages; after updating, see which services to restart.

Sources

Page generated automatically from official sources on 2026-11-03 18:05 UTC. Always confirm with your vendor's advisory.