← Vulnerability feed

Vulnerability record · CVE-2026-49422 · published 19 August 2026

CVE-2026-49422: Freebsd use after free vulnerability

Freebsd · Freebsd

The RACK setsockopt(2) handler drops the connection lock in order to copy option data from userspace, then reacquires the lock. After reacquiring, it verifies that the TCP stack had not been switched away, but did not reload its pointer to the stack's per-connection control block. If userspace switches stacks twice during this window, the check will succeed but the saved pointer will refer to freed memory. The bug may be exploitable by an unprivileged local user to escalate privileges.

8.4 CVSS 3.1 High EPSS 0.17% · top 94.6% CWE-416 · Use after free
8.4CVSS 3.1 base score
0.17%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
1References
1 Sep 2026Last modified by NVD

Description

The RACK setsockopt(2) handler drops the connection lock in order to copy option data from userspace, then reacquires the lock. After reacquiring, it verifies that the TCP stack had not been switched away, but did not reload its pointer to the stack's per-connection control block. If userspace switches stacks twice during this window, the check will succeed but the saved pointer will refer to freed memory. The bug may be exploitable by an unprivileged local user to escalate privileges.

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://security.freebsd.org/advisories/FreeBSD-SA-26:43.tcp.asc Vendor Advisory

Track CVE-2026-49422 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

10.0CVE-2024-43102Freebsd use after free vulnerabilityConcurrent removals of certain anonymous shared memory mappings by using the UMTX_SHM_DESTROY sub-request of UMTX_OP_SHM can lead to decreasing the r…EPSS 0.68%10.0CVE-2018-17160Freebsd out-of-bounds write vulnerabilityIn FreeBSD before 11.2-STABLE(r341486) and 11.2-RELEASE-p6, insufficient bounds checking in one of the device models provided by bhyve can permit a g…EPSS 3.3%10.0CVE-2014-3954Freebsd memory buffer overflow vulnerabilityStack-based buffer overflow in rtsold in FreeBSD 9.1 through 10.1-RC2 allows remote attackers to cause a denial of service (crash) or possibly execut…EPSS 3.9%10.0CVE-2011-4862telnetd encryption key buffer overflow allows remote code executionA buffer overflow in libtelnet/encrypt.c in telnetd affects FreeBSD 7.3 through 9.0, MIT krb5-appl 1.0.2 and earlier, Heimdal 1.5.1 and earlier, GNU …EPSS 95%analysed10.0CVE-2006-4304Freebsd vulnerabilityBuffer overflow in the sppp driver in FreeBSD 4.11 through 6.1, NetBSD 2.0 through 4.0 beta before 20060823, and OpenBSD 3.8 and 3.9 before 20060902 …EPSS 12%10.0CVE-2006-0226Freebsd vulnerabilityInteger overflow in IEEE 802.11 network subsystem (ieee80211_ioctl.c) in FreeBSD before 6.0-STABLE, while scanning for wireless networks, allows remo…EPSS 5.8%10.0CVE-2005-0708Dragonflybsd vulnerabilityThe sendfile system call in FreeBSD 4.8 through 4.11 and 5 through 5.4 can transfer portions of kernel memory if a file is truncated while it is bein…EPSS 2.3%10.0CVE-2004-0002Freebsd vulnerabilityThe TCP MSS (maximum segment size) functionality in netinet allows remote attackers to cause a denial of service (resource exhaustion) via (1) a low …EPSS 2.1%

Source: NIST National Vulnerability Database (record CVE-2026-49422), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.