CVE-2021-47106

Score / Severity

7.8

High

CVE Descriptions

netfilter: nf_tables: fix use-after-free in nft_set_catchall_destroy()

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: fix use-after-free in nft_set_catchall_destroy() We need to use list_for_each_entry_safe() iterator because we can not access @catchall after kfree_rcu() call. syzbot reported: BUG: KASAN: use-after-free in nft_set_catchall_destroy net/netfilter/nf_tables_api.c:4486 [inline] BUG: KASAN: use-after-free in nft_set_destroy net/netfilter/nf_tables_api.c:4504 [inline] BUG: KASAN: use-after-free in nft_set_destroy+0x3fd/0x4f0 net/netfilter/nf_tables_api.c:4493 Read of size 8 at addr ffff8880716e5b80 by task syz-executor.3/8871 CPU: 1 PID: 8871 Comm: syz-executor.3 Not tainted 5.16.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description.constprop.0.cold+0x8d/0x2ed mm/kasan/report.c:247 __kasan_report mm/kasan/report.c:433 [inline] kasan_report.cold+0x83/0xdf mm/kasan/report.c:450 nft_set_catchall_destroy net/netfilter/nf_tables_api.c:4486 [inline] nft_set_destroy net/netfilter/nf_tables_api.c:4504 [inline] nft_set_destroy+0x3fd/0x4f0 net/netfilter/nf_tables_api.c:4493 __nft_release_table+0x79f/0xcd0 net/netfilter/nf_tables_api.c:9626 nft_rcv_nl_event+0x4f8/0x670 net/netfilter/nf_tables_api.c:9688 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83 blocking_notifier_call_chain kernel/notifier.c:318 [inline] blocking_notifier_call_chain+0x67/0x90 kernel/notifier.c:306 netlink_release+0xcb6/0x1dd0 net/netlink/af_netlink.c:788 __sock_release+0xcd/0x280 net/socket.c:649 sock_close+0x18/0x20 net/socket.c:1314 __fput+0x286/0x9f0 fs/file_table.c:280 task_work_run+0xdd/0x1a0 kernel/task_work.c:164 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:175 [inline] exit_to_user_mode_prepare+0x27e/0x290 kernel/entry/common.c:207 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f75fbf28adb Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44 RSP: 002b:00007ffd8da7ec10 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00007f75fbf28adb RDX: 00007f75fc08e828 RSI: ffffffffffffffff RDI: 0000000000000003 RBP: 00007f75fc08a960 R08: 0000000000000000 R09: 00007f75fc08e830 R10: 00007ffd8da7ed10 R11: 0000000000000293 R12: 00000000002067c3 R13: 00007ffd8da7ed10 R14: 00007f75fc088f60 R15: 0000000000000032 Allocated by task 8886: kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:434 [inline] ____kasan_kmalloc mm/kasan/common.c:513 [inline] ____kasan_kmalloc mm/kasan/common.c:472 [inline] __kasan_kmalloc+0xa6/0xd0 mm/kasan/common.c:522 kasan_kmalloc include/linux/kasan.h:269 [inline] kmem_cache_alloc_trace+0x1ea/0x4a0 mm/slab.c:3575 kmalloc include/linux/slab.h:590 [inline] nft_setelem_catchall_insert net/netfilter/nf_tables_api.c:5544 [inline] nft_setelem_insert net/netfilter/nf_tables_api.c:5562 [inline] nft_add_set_elem+0x232e/0x2f40 net/netfilter/nf_tables_api.c:5936 nf_tables_newsetelem+0x6ff/0xbb0 net/netfilter/nf_tables_api.c:6032 nfnetlink_rcv_batch+0x1710/0x25f0 net/netfilter/nfnetlink.c:513 nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:634 [inline] nfnetlink_rcv+0x3af/0x420 net/netfilter/nfnetlink.c:652 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x904/0xdf0 net/netlink/af_netlink.c:1921 sock_sendmsg_nosec net/ ---truncated---

CVE Informations

Related Weaknesses

CWE-ID	Weakness Name	Source
CWE-416	Use After Free The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

Metrics

Metrics	Score	Severity	CVSS Vector	Source
V3.1	7.8	HIGH	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H More informations Base: Exploitabilty Metrics The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component. Attack Vector This metric reflects the context by which vulnerability exploitation is possible. Local The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Attack Complexity This metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability. Low Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component. Privileges Required This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability. Low The attacker requires privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources. User Interaction This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable component. None The vulnerable system can be exploited without interaction from any user. Base: Scope Metrics The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope. Scope Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources (e.g., files, CPU, memory) in a controlled manner. All the subjects and objects under the jurisdiction of a single security authority are considered to be under one security scope. If a vulnerability in a vulnerable component can affect a component which is in a different security scope than the vulnerable component, a Scope change occurs. Intuitively, whenever the impact of a vulnerability breaches a security/trust boundary and impacts components outside the security scope in which vulnerable component resides, a Scope change occurs. Unchanged An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority. Base: Impact Metrics The Impact metrics capture the effects of a successfully exploited vulnerability on the component that suffers the worst outcome that is most directly and predictably associated with the attack. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve. Confidentiality Impact This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability. High There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server. Integrity Impact This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. High There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component. Availability Impact This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. High There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable). Temporal Metrics The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence in the description of a vulnerability. Environmental Metrics These metrics enable the analyst to customize the CVSS score depending on the importance of the affected IT asset to a user’s organization, measured in terms of Confidentiality, Integrity, and Availability.	nvd@nist.gov

EPSS

EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.

EPSS Score

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

Date	EPSS V0	EPSS V1	EPSS V2 (> 2022-02-04)	EPSS V3 (> 2025-03-07)	EPSS V4 (> 2025-03-17)
2024-03-10	–	–	–	0.04%	–
2024-03-31	–	–	–	0.04%	–
2024-06-02	–	–	–	0.04%	–
2024-08-25	–	–	–	0.04%	–
2024-12-08	–	–	–	0.04%	–
2025-02-16	–	–	–	0.04%	–
2025-01-19	–	–	–	0.04%	–
2025-02-16	–	–	–	0.04%	–
2025-03-18	–	–	–	–	0.04%
2025-03-30	–	–	–	–	0.06%
2025-04-12	–	–	–	–	0.01%
2025-04-12	–	–	–	–	0.01,%

EPSS Percentile

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.

EPSS First.org

Date	Percentile
2024-03-10	7%
2024-03-31	8%
2024-06-02	9%
2024-08-25	1%
2024-12-08	11%
2025-02-16	12%
2025-01-19	11%
2025-02-16	12%
2025-03-18	11%
2025-03-30	15%
2025-04-12	1%
2025-04-12	1%