CVE-2026-101307
8.2HighPublished 15 Oct 2026 · NVD status: Undergoing Analysis · AI triage by gemini-3.8-flash
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
- Impact
- High impact on availability
- Weakness
- CWE-122, CWE-787
Impact
Remote unauthenticated attackers can crash the system via a kernel panic by establishing a TCP connection and flooding ACKs. This triggers a 512 KB kernel heap out-of-bounds write.
Root cause
A 16-bit allocation counter wraps to zero when doubling the PCM sample array in the TCP RACK stack, causing an undersized buffer allocation followed by an out-of-bounds copy.
Affected systems
Versions not listed — check the vendor advisory.
CVSS v4.0 · 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
Fix & remediation
Check FreeBSD advisory FreeBSD-SA-26:70.tcp.asc for patched releases and apply the provided kernel patch. As an interim workaround, disable the RACK TCP stack or switch connections to a different TCP congestion control algorithm.
$ freebsd-update fetch && freebsd-update installAI-suggested. Run it in staging first and check it against the vendor advisory. Why?
NVD description
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.