CVE-2026-64026 rxrpc: Fix DATA decrypt vs splice() by copying data to buffer in recvmsg
A memory corruption vulnerability in the Linux kernel's rxrpc subsystem allows attackers to cause pagecache corruption via splice(), potentially leading to code execution or privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-64026?
CVE-2026-64026 is a high-severity memory corruption vulnerability in Linux kernel, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
rxrpc: Fix DATA decrypt vs splice() by copying data to buffer in recvmsg
This improves the fix for CVE-2026-43500.
Fix the pagecache corruption from in-place decryption of a DATA packet transmitted locally by splice() by getting rid of the packet sharing in the I/O thread and unconditionally extracting the packet content into a bounce buffer in which the buffer is decrypted. recvmsg() (or the kernel equivalent) then copies the data from the bounce buffer to the destination buffer. The sk_buff then remains unmodified.
This has an additional advantage in that the packet is then arranged in the buffer with the correct alignment required for the crypto algorithms to process directly. The performance of the crypto does seem to be a little faster and, surprisingly, the unencrypted performance doesn't seem to change much - possibly due to removing complexity from the I/O thread.
Yet another advantage is that the I/O thread doesn't have to copy packets which would slow down packet distribution, ACK generation, etc..
The buffer belongs to the call and is allocated initially at 2K, sufficiently large to hold a whole jumbo subpacket, but the buffer will be increased in size if needed. However, to take this work, MSG_PEEK may cause a later packet to be decrypted into the buffer, in which case the earlier one will need re-decrypting for a subsequent recvmsg().
Note that rx_pkt_offset may legitimately see 0 as a valid offset now, so switch to using USHRT_MAX to indicate an invalid offset.
Note also that I would generally prefer to replace the buffers of the current sk_buff with a new kmalloc'd buffer of the right size, ditching the old data and frags as this makes the handling of MSG_PEEK easier and removes the re-decryption issue, but this looks like quite a complicated thing to achieve. skb_morph() looks half way to what I want, but I don't want to have to allocate a new sk_buff.
Which versions are affected by CVE-2026-64026?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64026?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-64026 being exploited?
There is no known exploitation of CVE-2026-64026 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-64026, DEBIAN-CVE-2026-64026, GHSA-97h7-gm2v-v84m, ROOT-OS-DEBIAN-11-CVE-2026-64026, ROOT-OS-DEBIAN-12-CVE-2026-64026, ROOT-OS-UBUNTU-2204-CVE-2026-64026 and 1 more.