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.
Published: 2026-07-19
Score: 7.8 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

The vulnerability arises when the rxrpc protocol performs in‑place decryption of a DATA packet that is forwarded locally via splice(). This action modifies the shared packet buffer during decryption, leading to pagecache corruption and kernel memory corruption. The weakness is improper handling of decryption with shared buffers, corresponding to CWE‑366.

Affected Systems

All Linux kernel implementations that use the rxrpc protocol without the bounce‑buffer decrypt fix before the patch date are affected. The vulnerable code path exists in any kernel where rxrpc processes DATA packets locally via splice() without isolating decryption from the shared buffer.

Risk and Exploitability

The CVSS score of 7.8 indicates high severity, while the EPSS score of less than 1% suggests a low likelihood of exploitation in the wild. The vulnerability is not listed in the CISA KEV catalog. An attacker would likely craft malicious rxrpc DATA packets and send them over the network to trigger the vulnerable splice/decryption path. Successful exploitation could lead to kernel memory corruption, potentially resulting in denial of service or other adverse effects.

Generated by OpenCVE AI on August 4, 2026 at 06:10 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Apply a Linux kernel update that includes the rxrpc decryption bounce‑buffer fix
  • If an update is not immediately possible, disable or restrict the use of the rxrpc protocol to limit exposure
  • Configure network filtering or firewall rules to block or limit incoming rxrpc traffic to trusted sources

Generated by OpenCVE AI on August 4, 2026 at 06:10 UTC.

Tracking

Sign in to view the affected projects.

Advisories
Source ID Title
Ubuntu USN Ubuntu USN USN-8593-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8603-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8618-1 Linux kernel vulnerabilities
History

Wed, 22 Jul 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-366
References
Metrics threat_severity

None

 threat_severity

Important

Mon, 20 Jul 2026 14:45:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

Sun, 19 Jul 2026 15:45:00 +0000

Type Values Removed Values Added
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.
Title rxrpc: Fix DATA decrypt vs splice() by copying data to buffer in recvmsg
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-08-05T12:38:20.972Z

Reserved: 2026-07-19T07:54:57.028Z

Link: CVE-2026-64026

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

Severity : Important

Publid Date: 2026-07-19T00:00:00Z

Links: CVE-2026-64026 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-08-04T06:15:04Z

Weaknesses
  • CWE-366

    Race Condition within a Thread