CVE-2026-49423Network attack vector

Kernel panic via uninitialized iovec read

Published Aug 19, 2026 · Updated Aug 19, 2026

Use of uninitialized memory in FreeBSD KTLS receive allows remote attackers to crash the kernel via a crafted TLS 1.2 CBC record. The ktls_ocf_tls_cbc_decrypt() function advances the iovec index for every mbuf in the chain, even mbufs skipped because they contain only the 5-byte TLS header, leaving uninitialized slots that later HMAC processing reads. Reachability requires receive-side KTLS with AES-CBC enabled and enough TCP segmentation control to place only the TLS record header in the first mbuf, and the consequence is a kernel panic rather than code execution.

CVSS severityUnavailable
Unscored
EPSS probability0.10%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use of uninitialized memory in FreeBSD KTLS receive allows remote attackers to crash the kernel via a crafted TLS 1.2 CBC record. The ktls_ocf_tls_cbc_decrypt() function advances the iovec index for every mbuf in the chain, even mbufs skipped because they contain only the 5-byte TLS header, leaving uninitialized slots that later HMAC processing reads. Reachability requires receive-side KTLS with AES-CBC enabled and enough TCP segmentation control to place only the TLS record header in the first mbuf, and the consequence is a kernel panic rather than code execution.

The record

CVE
CVE-2026-49423
Published
Aug 19, 2026
Updated
Aug 19, 2026
Vendor
The FreeBSD Project
Product
FreeBSD
Classifications
CWE-908, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=14.3-RELEASE <p16
  2. Affected versionversion=14.4-RELEASE <p7
  3. Affected versionversion=15.0-RELEASE <p11
  4. Affected versionversion=15.1-RELEASE <p1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The FreeBSD Project · FreeBSDversion=14.3-RELEASE <p16; version=14.4-RELEASE <p7; version=15.0-RELEASE <p11; version=15.1-RELEASE <p1

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-908Use of Uninitialized Resource
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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