CVE-2026-53077: Linux Kernel Privilege Escalation Flaw

CVE-2026-53077 Overview

CVE-2026-53077 is a Linux kernel vulnerability in the Reliable Datagram Sockets (RDS) over InfiniBand (IB) subsystem. The net/rds code did not properly restrict RDS/IB usage to the initial network namespace. Using RDS/IB from non-initial network namespaces leads to incorrect behavior because the existing implementation was not designed to operate across multiple namespaces. The upstream fix prevents net/rds from being used in any network namespace other than init_net. This issue affects container and namespace-isolated environments where RDS sockets may be exposed to unprivileged workloads.

Critical Impact
Unsanctioned use of RDS/IB outside the initial network namespace can produce undefined kernel behavior, impacting reliability and isolation guarantees in containerized Linux deployments.

Affected Products

Linux kernel (net/rds subsystem with InfiniBand transport)
Distributions shipping vulnerable kernels with RDS/IB enabled
Container hosts using network namespaces with RDS modules loadable

Discovery Timeline

2026-06-24 - CVE-2026-53077 published to NVD
2026-06-24 - Last updated in NVD database

Technical Details for CVE-2026-53077

Vulnerability Analysis

The Reliable Datagram Sockets protocol provides connection-oriented, reliable datagram messaging between hosts, with an InfiniBand transport (rds_ib) layered on the kernel RDMA stack. The RDS/IB implementation was authored against the initial network namespace init_net and assumes global state for connection tracking, device binding, and IB device lookup. When an AF_RDS socket is created inside a non-initial namespace, the code paths still operate on global structures, causing namespace boundaries to be ignored.

The upstream commits restrict creation and binding of RDS/IB resources to init_net, returning an error when the calling task resides in another namespace. This is a defense-in-depth correction that closes a namespace confusion class of issue [CWE-incorrect-resource-transfer-between-spheres] in the kernel networking stack.

Root Cause

The root cause is missing namespace validation in the RDS/IB transport. Code paths that allocate connections and bind IB devices reference initial-namespace data without checking the caller's net pointer. Multiple commits, including 07035306, 3174fc70, 3e7f14cd, a7494479, b6a54f5e, c244b79a, ebf71dd4, and fb407343, apply the restriction across stable branches.

Attack Vector

A process inside a non-initial network namespace, such as a container, that has the ability to create AF_RDS sockets can exercise the unrestricted code path. The vulnerability does not require remote network access. Local invocation through the socket API is sufficient to reach the affected code. NVD lists no CVSS vector for this entry, and no public proof-of-concept is referenced.

The vulnerability is described in prose only because no verified exploit code is published. See the Linux Kernel Commit 07035306 for the canonical fix.

Detection Methods for CVE-2026-53077

Indicators of Compromise

Unexpected loading of the rds or rds_rdma kernel modules on container hosts that do not require RDS
Audit records showing socket(AF_RDS, ...) calls originating from processes inside non-initial network namespaces
Kernel log warnings or oopses referencing net/rds/ib* functions following socket activity from containers

Detection Strategies

Enable Linux audit rules on the socket syscall filtering for a0=21 (AF_RDS) and correlate with the originating PID namespace and network namespace
Inventory hosts where CONFIG_RDS and CONFIG_RDS_RDMA are enabled in the running kernel using zcat /proc/config.gz or /boot/config-$(uname -r)
Use eBPF tracing on rds_create and rds_ib_* symbols to flag invocations where current->nsproxy->net_ns != &init_net

Monitoring Recommendations

Track kernel package versions against vendor advisories that reference the listed stable commits
Alert on container runtimes attempting to create RDS sockets, which is uncommon in normal workloads
Monitor dmesg for RDS subsystem errors after kernel updates to confirm the namespace restriction is enforced

How to Mitigate CVE-2026-53077

Immediate Actions Required

Apply the stable kernel update from your distribution that incorporates the RDS/IB namespace restriction commits
Blacklist the rds and rds_rdma modules on hosts that do not require RDS functionality
Restrict container capabilities so workloads cannot load kernel modules or create unusual socket families

Patch Information

The fix is published in the upstream Linux kernel through commits 07035306, 3174fc70, 3e7f14cd, a7494479, b6a54f5e, c244b79a, ebf71dd4, and fb407343. Update to a distribution kernel that backports these commits.

Workarounds

Prevent loading of the RDS modules using /etc/modprobe.d/ blacklist entries on hosts without an RDS workload
Apply seccomp profiles to containers that deny the socket syscall for AF_RDS (family 21)
Use SELinux or AppArmor policies to restrict which processes may open RDS sockets

bash

# Blacklist RDS modules on systems that do not use the RDS protocol
cat <<EOF | sudo tee /etc/modprobe.d/blacklist-rds.conf
blacklist rds
blacklist rds_rdma
blacklist rds_tcp
install rds /bin/true
EOF

# Verify the modules are not currently loaded
lsmod | grep -E '^rds'

# Confirm running kernel version after patching
uname -r