TI-2026-74629 Aliases CVE-2026-101307 GHSA-gpr4-gr7v-w9p3

Remotely triggerable heap buffer overflow in FreeBSD tcp_rack

LOW 35CWE-122Published 2026-10-15 · Updated 2026-10-15

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Attack requirements: Present
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Fixed

Attack profile from CVSS 4.0 · CISA ADP. Fix status from CNA. Impact type from CWE-122 and the CVSS impact.

Summary

The RACK stack in FreeBSD's tcp_rack module doubles a 16-bit allocation counter when the PCM sample array must grow. Repeated doublings wrap the counter to zero, so the kernel allocates a near-zero-length buffer and then copies the existing samples into it. A remote peer can trigger this expansion by sending enough ACKs on an established connection, and an attacker who can open a TCP connection to a system using the RACK stack can cause an out-of-bounds write of about 512 KB in the kernel heap, possibly causing a kernel panic. The weaknesses are CWE-122 and CWE-787.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00313 24th percentileScored 2026-11-07

Fix Fixed FreeBSD (FreeBSD): p5

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
FreeBSD	FreeBSD	15.1-RELEASE to before p5	p5	Patch available	CNA

FreeBSD VendorFreeBSD Affected 15.1-RELEASE to before p5 Fixed in p5 Patch available CNA

CPE configurations NVD · 5

CPE	Versions	Role	Vendor
cpe:2.3:o:freebsd:freebsd:15.1:-::::::	15.1	Vulnerable	FreeBSD
cpe:2.3:o:freebsd:freebsd:15.1:p1::::::	15.1 p1	Vulnerable	FreeBSD
cpe:2.3:o:freebsd:freebsd:15.1:p2::::::	15.1 p2	Vulnerable	FreeBSD
cpe:2.3:o:freebsd:freebsd:15.1:p3::::::	15.1 p3	Vulnerable	FreeBSD
cpe:2.3:o:freebsd:freebsd:15.1:p4::::::	15.1 p4	Vulnerable	FreeBSD

cpe:2.3:o:freebsd:freebsd:15.1:-:*:*:*:*:*:* Versions 15.1 Vulnerable ·FreeBSD
cpe:2.3:o:freebsd:freebsd:15.1:p1:*:*:*:*:*:* Versions 15.1 p1 Vulnerable ·FreeBSD
cpe:2.3:o:freebsd:freebsd:15.1:p2:*:*:*:*:*:* Versions 15.1 p2 Vulnerable ·FreeBSD
cpe:2.3:o:freebsd:freebsd:15.1:p3:*:*:*:*:*:* Versions 15.1 p3 Vulnerable ·FreeBSD
cpe:2.3:o:freebsd:freebsd:15.1:p4:*:*:*:*:*:* Versions 15.1 p4 Vulnerable ·FreeBSD

Remediation

Upgrade FreeBSD 15.1-RELEASE to p5 or later. The fix is available in p5, and systems before p5 in the 15.1-RELEASE line are affected.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Fix · CNA FreeBSD (FreeBSD) Fixed in p5

Timeline

2026-10-15 Threatist record created from CVE-2026-101307
2026-10-16 Alias added: GHSA-gpr4-gr7v-w9p3
2026-10-20 CVSS score added · NVD

References

Patch 1

https://security.freebsd.org/advisories/FreeBSD-SA-26:70.tcp.asc

TI-2011-04182 Buffer overflow in libtelnet/encrypt.c in telnetd in FreeBSD 7.3 through 9.0, MIT… CVSS 2.0HIGH 10.0
TI-2007-03684 Integer overflow in print-bgp.c in the BGP dissector in tcpdump 3.9.6 and earlier allows… CVSS 3.1CRITICAL 9.8
TI-2002-00376 Integer overflow in xdr_array function in RPC servers for operating systems that use… CVSS 3.1CRITICAL 9.8
TI-2024-05929 Openssh: regresshion - race condition in ssh allows rce/dos CVSS 3.1HIGH 8.1
TI-2003-00437 Off-by-one error in the fb_realpath() function, as derived from the realpath function in… CVSS 3.1CRITICAL 9.8
TI-2003-00642 The prescan function in Sendmail 8.12.9 allows remote attackers to execute arbitrary code… CVSS 2.0HIGH 10.0

See all 576 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences