alt Hacker NewsWorse yet, the Ubuntu security incident page[0] lists "Ubuntu Priority: High" (as opposed to Critical, which would trigger an out-of-schedule patch). There's a "Why this priority?" link that simply says:
> Why is this CVE high priority?
> See ubuntu cvss score
That's it, we don't even get a period on this TBD of a sentence. It's followed by a generic link that explains what "Ubuntu Priority" is, but that page contradicts their choice. Note that it doesn't offer any mitigations either, and even the (horrendously unclear) description is copied from the NIST page, so there's no actual message from Ubuntu.
I already had a bad feeling the first time I saw "Get more security updates through Ubuntu Pro" on `apt upgrade`, this is now the kick I needed to move to a different distro.
[0] https://ubuntu.com/security/CVE-2026-98432#priority-reason
Replies
Yeah, their lack of a satisfactory response is the final nail in their coffin. This incident escalates my consulting advice about Ubuntu from “not recommended” to “switch immediately”.
Some of my clients may be surprised by this change, as I once advocated for Ubuntu as a good choice for a development and deployment platform. While that has not been true for quite a while, they have now jumped the shark into eel-infested waters; I cannot take them seriously any longer.
> I already had a bad feeling the first time I saw "Get more security updates through Ubuntu Pro" on `apt upgrade`, this is now the kick I needed to move to a different distro.
To be clear, Ubuntu Pro doesn't have the fix yet either.
Moved to Debian few years back and never looked back. We used Ubuntu for a bunch of clients and unfortunately had to let them know they will have to migrate to Debian or similar. It's such a shame because I really used to love Ubuntu until Canonical started turning slowly into your typical everyday corporate.
The more I look at this the angrier I get. This is a CVE that Anthropic claims can get a Remote Code Execution on vulnerable systems, which includes default Ubuntu installs running any sort of Go server like Caddy. Bad enough that I shut down my personal website and self-hosted tools (sorry for any typos, my grammar checker is also down).
And this is how Ubuntu describes the vulnerability to sysadmins:
In the Linux kernel, the following vulnerability has been resolved:
ipv4: free inet_opt and ireq_opt after an RCU grace period
tcp_v4_syn_recv_sock() transfers ownership of ireq->ireq_opt to the
child socket (newinet->inet_opt) without copying it.
Another cpu can concurrently process a retransmitted SYN for the same
request socket, and send a SYNACK from tcp_check_req().
tcp_v4_send_synack() and inet_csk_route_req() read ireq->ireq_opt
under rcu_read_lock() only, and ip_build_and_send_pkt() and
ip_options_build() then read opt->optlen twice.
Note that the SYNACK timer itself is not an issue: it holds a
reference on its request socket, and inet_csk_reqsk_queue_drop()
calls timer_delete_sync() before the child can be freed.
Since commit 079096f103fa (“tcp/dccp: install syn_recv requests
into ehash table”), request sockets are processed without holding
the listener lock, so nothing prevents the child socket from being
freed while the SYNACK is still being built. TCP child sockets do
not have SOCK_RCU_FREE, and inet_sock_destruct() frees inet_opt
with a plain kfree(), leading to a use-after-free in
ip_options_build().
A similar issue exists with request socket migration
(net.ipv4.tcp_migrate_req=1, or a BPF_SK_REUSEPORT_SELECT_OR_MIGRATE
program). reqsk_timer_handler() clones the request socket with
inet_reqsk_clone(), so that the old request socket and its clone
share the same ireq_opt, then reqsk_migrate_reset() clears the
pointer in the old one. Another cpu holding a reference on the old
request socket can still be using these options (sending a SYNACK,
or creating a child in tcp_v4_syn_recv_sock()) when the clone is
freed, and tcp_v4_reqsk_destructor() also uses a plain kfree().
Readers already use RCU, and other paths replacing inet_opt
(do_ip_setsockopt(), cipso_v4_sock_setattr()...) already use
kfree_rcu(). Use kfree_rcu() in inet_sock_destruct() and
tcp_v4_reqsk_destructor() as well.
IPv6 is not affected by the first issue, because tcp_v6_syn_recv_sock()
duplicates the options. tcp_v6_reqsk_destructor() has the same
migration issue with ipv6_opt, which is only set by CALIPSO. This
will be addressed in a separate patch.
As far as I know the only working exploit is working on machine with MultiTCP enabled. Redhat also downgraded the issue to "high" and also did not release a patch yet. I would have preferred a patch but I accept that they know better than me what they are doing.
> I already had a bad feeling the first time I saw "Get more security updates through Ubuntu Pro" on `apt upgrade`
To be clear, Ubuntu Pro doesn't have the fix yet either, in case anyone's confused.
They're totally asleep at the wheel, it's malpractice. The pitch for RHEL is highly competent maintenance you can't get elsewhere
I believe RHEL/Alma/Rocky has released patches today. I have a notice about they have done so.
Is RHEL really unpatched still? Looks like patches came yesterday: https://access.redhat.com/security/cve/cve-2026-98432
I use NixOS btw
I don't think this is fair. They don't do a good job of pointing you at their rationale which is in their security score here[0]. I ultimately had to have claude translate the kernelese in to something my small brain could understand but this is a bug that could crash your system but is unlikely to expose your confidential system data to attackers or degrade data on the system. Especially given that the exploit can only be done if packets with IP options. IP options are commonly dropped or removed from packets on the open web. You not only need a vulnerable system but a vulnerable request path through the internet which you would only know by trying this attack which is very timing dependent with the SYN,Retransmitted SYN and Reset all happening very close together. A motivated attacker could probably do this on your network but over the internet ... It sounds unlikely.
[0]https://ubuntu.com/security/CVE-2026-98432#impact-score