Out-of-Bounds Read in Linux kernel (CVE-2021-46992)
Summary
Vulnerability in Linux kernel (CVE-2021-46992). 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:
netfilter: nftables: avoid overflows in nft_hash_buckets()
Number of buckets being stored in 32bit variables, we have to
ensure that no overflows occur in nft_hash_buckets()
syzbot injected a size == 0x40000000 and reported:
UBSAN: shift-out-of-bounds in ./include/linux/log2.h:57:13
shift exponent 64 is too large for 64-bit type 'long unsigned int'
CPU: 1 PID: 29539 Comm: syz-executor.4 Not tainted 5.12.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x141/0x1d7 lib/dump_stack.c:120
ubsan_epilogue+0xb/0x5a lib/ubsan.c:148
__ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:327
__roundup_pow_of_two include/linux/log2.h:57 [inline]
nft_hash_buckets net/netfilter/nft_set_hash.c:411 [inline]
nft_hash_estimate.cold+0x19/0x1e net/netfilter/nft_set_hash.c:652
nft_select_set_ops net/netfilter/nf_tables_api.c:3586 [inline]
nf_tables_newset+0xe62/0x3110 net/netfilter/nf_tables_api.c:4322
nfnetlink_rcv_batch+0xa09/0x24b0 net/netfilter/nfnetlink.c:488
nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:612 [inline]
nfnetlink_rcv+0x3af/0x420 net/netfilter/nfnetlink.c:630
netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1338
netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1927
sock_sendmsg_nosec net/s…
Source: NIST National Vulnerability Database NVD
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-2021-46992 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-2021-46992" on the vendor's site.
CVE-2021-46992 (Linux kernel) — CWE-125 / 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.
Out-of-bounds read (CWE-125) 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-2021-46992 linux Fixed in: 5.10.38-1
- Ubuntu UBUNTU-CVE-2021-46992 linux-azure Fixed in: 4.15.0-1121.134~14.04.1
References
- patch git.kernel.org
- patch git.kernel.org
- patch git.kernel.org
- patch git.kernel.org
- patch git.kernel.org
- patch git.kernel.org
- patch git.kernel.org