Use-After-Free in Linux kernel (CVE-2021-47196)
Summary
Vulnerability in Linux kernel (CVE-2021-47196). Successful exploitation can lead to full system takeover.
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
RDMA/core: Set send and receive CQ before forwarding to the driver
Preset both receive and send CQ pointers prior to call to the drivers and
overwrite it later again till the mlx4 is going to be changed do not
overwrite ibqp properties.
This change is needed for mlx5, because in case of QP creation failure, it
will go to the path of QP destroy which relies on proper CQ pointers.
BUG: KASAN: use-after-free in create_qp.cold+0x164/0x16e [mlx5_ib]
Write of size 8 at addr ffff8880064c55c0 by task a.out/246
CPU: 0 PID: 246 Comm: a.out Not tainted 5.15.0+ #291
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
Call Trace:
dump_stack_lvl+0x45/0x59
print_address_description.constprop.0+0x1f/0x140
kasan_report.cold+0x83/0xdf
create_qp.cold+0x164/0x16e [mlx5_ib]
mlx5_ib_create_qp+0x358/0x28a0 [mlx5_ib]
create_qp.part.0+0x45b/0x6a0 [ib_core]
ib_create_qp_user+0x97/0x150 [ib_core]
ib_uverbs_handler_UVERBS_METHOD_QP_CREATE+0x92c/0x1250 [ib_uverbs]
ib_uverbs_cmd_verbs+0x1c38/0x3150 [ib_uverbs]
ib_uverbs_ioctl+0x169/0x260 [ib_uverbs]
__x64_sys_ioctl+0x866/0x14d0
do_syscall_64+0x3d/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
Allocated by task 246:
kasan_save_stack+0x1b/0x40
__kasan_kmalloc+0xa4/0xd0
create_qp.part.0+0x92/0x6a0 [ib_core]
ib_create_qp_user+0x97/0x150 [ib_core]
ib_uverbs_handler_UVERBS_METHOD_QP_CREAT…
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-2021-47196 has been found in Linux kernel.
Successful exploitation can lead to full system takeover. CVSS score: 7.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2021-47196" on the vendor's site.
CVE-2021-47196 (Linux kernel) — CWE-416 / CVSS v3 7.8
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.
Use-after-free (CWE-416) exists in Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: High (CVSS 7.8/10). Successful exploitation can lead to full system takeover.
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。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2021-47196 linux Fixed in: 5.15.5-1
- Ubuntu UBUNTU-CVE-2021-47196 linux-hwe-edge
References
- patch git.kernel.org
- patch git.kernel.org
- web nvd.nist.gov
- web github.com