Vulnerability in Linux kernel (CVE-2026-52939)
Summary
Vulnerability in Linux kernel (CVE-2026-52939). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
net/rds: fix NULL deref in rds_ib_send_cqe_handler() on masked atomic completion
rds_ib_xmit_atomic() always programs a masked atomic opcode
(IB_WR_MASKED_ATOMIC_CMP_AND_SWP or IB_WR_MASKED_ATOMIC_FETCH_AND_ADD)
for every RDS atomic cmsg. But the completion-side switch in
rds_ib_send_unmap_op() only handles the non-masked opcodes, so a masked
atomic completion falls through to default and returns rm == NULL while
send->s_op is left set. rds_ib_send_cqe_handler() then dereferences the
NULL rm via rm->m_final_op, oopsing in softirq context. An unprivileged
AF_RDS sendmsg() of an atomic cmsg over an active RDS/IB connection
triggers it; on hardware that natively accepts masked atomics (mlx4,
mlx5) no extra setup is needed.
RDS/IB: rds_ib_send_unmap_op: unexpected opcode 0xd in WR!
Oops: general protection fault [#1] SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000190-0x0000000000000197]
RIP: rds_ib_send_cqe_handler+0x25c/0xb10 (net/rds/ib_send.c:282)
Call Trace:
rds_ib_send_cqe_handler (net/rds/ib_send.c:282)
poll_scq (net/rds/ib_cm.c:274)
rds_ib_tasklet_fn_send (net/rds/ib_cm.c:294)
tasklet_action_common (kernel/softirq.c:943)
handle_softirqs (kernel/softirq.c:573)
run_ksoftirqd (kernel/softirq.c:479)
Kernel panic - not syncing: Fatal exception in interrupt
Handle the masked atomic opcodes in the same case as the non-masked
ones: they map to the same struct…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-52939 has been found in Linux kernel.
Risk of unauthorized operations or information disclosure. CVSS score: 5.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-52939" on the vendor's site.
CVE-2026-52939 (Linux kernel) — CWE-476 / CVSS v3 5.5
Attack vector: local / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-476) exists in Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: Medium (CVSS 5.5/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。
-
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-52939 linux Fixed in: 6.1.176-1
- Ubuntu UBUNTU-CVE-2026-52939 linux
References
- advisory nvd.nist.gov
- advisory github.com
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web github.com