CVE-2026-49423: When building the iovec array for a received TLS 1.2 CBC record, ktls_ocf_tls_cbc_decrypt() incremented the io

Routine

LOW 3.3MITIGATE

CVE-2026-49423 is a low-severity flaw (CVSS 3.3) affecting freebsd. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

When building the iovec array for a received TLS 1.2 CBC record, ktls_ocf_tls_cbc_decrypt() incremented the iovec index for every mbuf in the chain, including mbufs that were skipped because they contained only TLS header bytes. This left uninitialized entries in the iovec array. The iovec array was allocated without zeroing. A remote TLS peer can cause the kernel to read from uninitialized iovec entries during HMAC computation, resulting in a

Why this priority

No elevated risk signals yet

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	3.3 (Low)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.1% (top 97%)
CISA exploited list	No
Weakness	CWE-908
Published	2026-08-19
Last modified	2026-08-31

Publisher (CNA): FreeBSD · Vendor: freebsd

Last updated 2026-08-31 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-19 07:16 UTCPublished CVE record published
2026-08-31 19:01 UTCUpdated Record last modified

freebsd freebsd MITIGATE

Affected: 14.3 · 14.3 p1 · 14.3 p10 · 14.3 p11 · 14.3 p12 · 14.3 p13 · 14.3 p14 · 14.3 p15

Fixed in: no fixed release known

Safe to downgrade to: a release before 14.3

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-49423?

freebsd: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-49423 being exploited?

CVE-2026-49423 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-49423 affect?

CVE-2026-49423 affects freebsd. Severity is low (CVSS 3.3). When building the iovec array for a received TLS 1.2 CBC record, ktls_ocf_tls_cbc_decrypt() incremented the iovec index for every mbuf in the chain, including mbufs that were skipped because they contained only TLS header bytes. This left

How urgent is CVE-2026-49423?

Priority 12/100. No elevated risk signals yet.

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References

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