CVE-2026-64459: In the Linux kernel, the following vulnerability has been resolved: tcp: restore RCU grace period in tcp_ao_d

This month

CRITICAL 9.8REMOTEWATCHLIST

CVE-2026-64459 is a critical-severity flaw (CVSS 9.8) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In the Linux kernel, the following vulnerability has been resolved: tcp: restore RCU grace period in tcp_ao_destroy_sock Commit 51e547e8c89c ("tcp: Free TCP-AO/TCP-MD5 info/keys without RCU") removed the call_rcu() callback from tcp_ao_destroy_sock(), arguing that "the destruction of info/keys is delayed until the socket destructor" and therefore "no one can discover it anymore". That argument does not hold for the call site in tcp_connect() (

Why this priority

Critical severity
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 49%)
CISA exploited list	No
Published	2026-07-25
Last modified	2026-08-17

Publisher (CNA): kernel.org

Last updated 2026-08-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Timeline

2026-07-25 10:17 UTCPublished CVE record published
2026-08-17 05:17 UTCUpdated Record last modified

Exact fixes by distribution

Fedora 46 · gcl · FIXED · 2.7.1-12.fc46 · FEDORA-2026-ff383a759b · source

sudo dnf upgrade --advisory=FEDORA-2026-ff383a759b

Fedora ELN · mozjs140 · FIXED · 140.13.0-5.eln159 · FEDORA-2026-f7ed0026e0 · source

sudo dnf upgrade --advisory=FEDORA-2026-f7ed0026e0

Ubuntu 20.04 · linux · NOT AFFECTED

Ubuntu 22.04 · linux · NOT AFFECTED

Ubuntu 24.04 · linux · NOT AFFECTED

Ubuntu 20.04 · linux-hwe-5.15 · NOT AFFECTED

Ubuntu 22.04 · linux-hwe-6.8 · NOT AFFECTED

Debian 12 · linux · NOT AFFECTED

Debian 13 · linux · NOT AFFECTED

RHEL 10 · kernel · NOT AFFECTED

RHEL 6 · kernel · NOT AFFECTED

RHEL 7 · kernel · NOT AFFECTED

RHEL 7 · kernel-rt · NOT AFFECTED

RHEL 8 · kernel · NOT AFFECTED

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-2045 · source

sudo dnf update --advisory=ALAS2023-2026-2045

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-2026-64459?

No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.

Is CVE-2026-64459 being exploited?

CVE-2026-64459 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-2026-64459 affect?

CVE-2026-64459 affects affected software. Severity is critical (CVSS 9.8). In the Linux kernel, the following vulnerability has been resolved: tcp: restore RCU grace period in tcp_ao_destroy_sock Commit 51e547e8c89c ("tcp: Free TCP-AO/TCP-MD5 info/keys without RCU") removed the call_rcu() callback from tcp_ao_de

How urgent is CVE-2026-64459?

Priority 57/100. Critical severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Linux kernel vulnerabilities

References

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