NVD / CVE Program· CNA freebsd

CVE-2026-49422: Use-after-free in TCP RACK stack option handler

Noroxi assessment

Priority: Monitor (action score 33/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.16% (FIRST EPSS).
Someone with local access to the system can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
Fixed version: FreeBSD FreeBSD p1, p11, p16.

Low priority for now. Upgrade to FreeBSD FreeBSD p1, p11, p16 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 8.4 · v3.1—No exploit Fix available

Published: Aug 19, 2026
Updated: Sep 1, 2026
EPSS: 0.1% · 5th percentile
CWE: CWE-416

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 33 / 40 · 8.4 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.1%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Running WordPress? Scan your site free with WP Lens

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

We use this product, ask for help

Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
freebsd	freebsd	cpe:2.3:o:freebsd:freebsd

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

freebsd freebsd14.3
freebsd freebsd14.4
freebsd freebsd15.0
freebsd freebsd15.1

Versions reported by the vendor

Affected version ranges reported by the assigning authority (freebsd). Independent of NVD's CPE analysis and usually ahead of it.

FreeBSD FreeBSD
- 15.1-RELEASE and later · before p1affected · release
- 15.0-RELEASE and later · before p11affected · release
- 14.4-RELEASE and later · before p7affected · release
- 14.3-RELEASE and later · before p16affected · release

Same product

freebsd: all records

Other highest-scoring records for the same primary product.

CVE-2020-7457In FreeBSD 12.1-STABLE before r359565, 12.1-RELEASE before p7, 11.4-STABLE before r362975, 11.4-RELEASE before p1, and 11.3-RELEASE before p
60This week
CVE-2006-0900nfsd in FreeBSD 6.0 kernel allows remote attackers to cause a denial of service via a crafted NFS mount request, as demonstrated by the Prot
51Plan
CVE-2018-17157In FreeBSD before 11.2-STABLE(r340854) and 11.2-RELEASE-p5, an integer overflow error when handling opcodes can cause memory corruption by s
46Plan

Published before and after this one in the same product

← EarlierCVE-2026-49420Aug 19, 2026 · Buffer overflow in libalias RTSP handler
35Monitor
← EarlierCVE-2026-49421Aug 19, 2026 · unlinkat(2) ignores AT_RESOLVE_BENEATH flag
28Monitor
Later →CVE-2026-49426Aug 19, 2026 · Incorrect audit records for ptrace(2) syscall requests
13Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
FreeBSD FreeBSD	p1	Vendor (CNA)
FreeBSD FreeBSD	p11	Vendor (CNA)
FreeBSD FreeBSD	p16	Vendor (CNA)
FreeBSD FreeBSD	p7	Vendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Maik MuenchSecfault Securityfinder

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

CVE-2026-494180 days apartUse-after-free in device pager page list
35Monitor
CVE-2026-580830 days apartUse-after-free in kqueue copy-on-fork
33Monitor
CVE-2026-5398120 days apartKernel use-after-free bug in the TIOCNOTTY handler
33Monitor
CVE-2026-580907 days apartUse-after-free in unix SOCK_STREAM message handling
31Monitor
CVE-2026-580917 days apartKernel use-after-free via the SNDCTL_DSP_SYNCSTART ioctl
31Monitor
CVE-2026-4941253 days apartUse-after-free bug in the IPV6_MSFILTER socket option handler
31Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Someone with local access to the system can trigger it.
No account or password is required.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Attack vector: Local
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

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

nvd-secondary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

Fix✗ → ✓Sep 28, 2026, 10:11 PM UTC

For records you follow, these changes also arrive as notifications. →

References

security.freebsd.org/advisories/FreeBSD-SA-26:43.tcp.asc

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records