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CVE-2026-49422

Use-after-free in TCP RACK stack option handler

HIGH
8.4
CVSS Score
Published: August 19, 2026 at 05:28 AM UTC
Updated: September 1, 2026 at 08:31 PM UTC
1 product affected across 1 vendorFreeBSD

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Severity
HIGH8.4
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

FreeBSD· Freebsd
95%
14.3-RELEASE ≤ v < p1614.4-RELEASE ≤ v < p715.0-RELEASE ≤ v < p1115.1-RELEASE ≤ v < p114.314.3 p114.3 p1014.3 p1114.3 p1214.3 p1314.3 p1414.3 p1514.3 p214.3 p314.3 p414.3 p514.3 p614.3 p714.3 p814.3 p914.3-RELEASE14.414.4 p114.4 p214.4 p314.4 p414.4 p514.4 p614.4 rc114.4-RELEASE15.015.0 p115.0 p1015.0 p215.0 p315.0 p415.0 p515.0 p615.0 p715.0 p815.0 p915.0-RELEASE15.115.1 rc215.1 rc3-p115.1-RELEASE
Affected range stops below p1, so it looks safe — our inference, not a vendor statement
Affected range stops below p11, so it looks safe — our inference, not a vendor statement
Affected range stops below p16, so it looks safe — our inference, not a vendor statement
Affected range stops below p7, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (1)

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

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.4HIGHCISA-ADP
Attack Vector
LOCAL
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-416

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