SB2026050502 - Red Hat Enterprise Linux 10 update for kernel
Published: May 5, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 4 secuirty vulnerabilities.
1) Use After Free (CVE-ID: CVE-2026-23270)
The vulnerability allows a local user to cause a use-after-free condition.
The vulnerability exists due to improper memory management in the act_ct action handling within the net/sched subsystem when processing packets in the egress path. A local user can attach the act_ct action to non-clsact/ingress qdiscs and trigger packet classification that returns TC_ACT_CONSUMED while the socket buffer (skb) is still held by the defragmentation engine, leading to a use-after-free condition.
The vulnerability specifically arises when act_ct is used in contexts not designed to handle TC_ACT_CONSUMED, particularly outside clsact/ingress qdiscs and shared blocks. Exploitation requires the ability to configure traffic control (tc) actions, implying local access and privileges to modify qdisc configurations.
2) Heap-based buffer overflow (CVE-ID: CVE-2026-31402)
The vulnerability allows a remote attacker to corrupt heap memory.
The vulnerability exists due to a heap-based buffer overflow in the NFSv4.0 LOCK replay cache when encoding denied LOCK operation responses. A remote attacker can trigger conflicting lock requests with a large lock owner value to corrupt heap memory.
The issue is caused by copying an encoded LOCK denied response into a fixed 112-byte inline replay buffer without sufficient bounds checking, resulting in a slab out-of-bounds write of up to 944 bytes. Exploitation requires two cooperating NFSv4.0 clients and can be performed remotely without authentication.
3) Use-after-free (CVE-ID: CVE-2026-31419)
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a use-after-free in bond_xmit_broadcast() when transmitting broadcast packets during concurrent slave enslave or release operations. A local user can trigger concurrent network interface state changes and packet transmission to cause a denial of service.
The issue arises because the determination of the last slave can change during RCU-protected iteration, leading to double consumption and double free of the original skb.
4) Improper control of a resource through its lifetime (CVE-ID: CVE-2026-31431)
The vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to improper memory handling within the authencesn cryptographic template in algif_aead when processing AEAD operations. A local user can trigger the vulnerable code path to execute arbitrary code on the system.
Note, this vulnerability was dubbed "Copy Fail".
Remediation
Install update from vendor's website.