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CVE-2023-53821— ip6_vti: fix slab-use-after-free in decode_session6

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于ip6_vti设备在发送IPv6包时可能触发释放后重用。

AI Predicted 6.6 Difficulty: Moderate EPSS 0.26% · P16

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux f855691975bb06373a98711e4cfe2c224244b536< 0f0ab8d52ee0062b28367dea23c29e254a26d7db affected
f855691975bb06373a98711e4cfe2c224244b536< fa6c6c04f6c9b21b315023f487e5a07ae7fcf647 affected
f855691975bb06373a98711e4cfe2c224244b536< eb47e612e59c358c3968a92f90dd36c78c9a2106 affected
f855691975bb06373a98711e4cfe2c224244b536< ec23b25e5687dbd644c0f57bcb6af22dd5a6dd36 affected
f855691975bb06373a98711e4cfe2c224244b536< a1639a82ce14af76b6419778d343ccbff86ee626 affected
f855691975bb06373a98711e4cfe2c224244b536< 55ad2309205cc00c585344374c7472420e1b2c12 affected
f855691975bb06373a98711e4cfe2c224244b536< c070688bfbe7759e61e697e421b2a331b0dd74bc affected
f855691975bb06373a98711e4cfe2c224244b536< 9fd41f1ba638938c9a1195d09bc6fa3be2712f25 affected
… +10 more rows
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I. Basic Information for CVE-2023-53821

Vulnerability Information
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Vulnerability Title
ip6_vti: fix slab-use-after-free in decode_session6
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ip6_vti: fix slab-use-after-free in decode_session6 When ipv6_vti device is set to the qdisc of the sfb type, the cb field of the sent skb may be modified during enqueuing. Then, slab-use-after-free may occur when ipv6_vti device sends IPv6 packets. The stack information is as follows: BUG: KASAN: slab-use-after-free in decode_session6+0x103f/0x1890 Read of size 1 at addr ffff88802e08edc2 by task swapper/0/0 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.4.0-next-20230707-00001-g84e2cad7f979 #410 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33 04/01/2014 Call Trace: <IRQ> dump_stack_lvl+0xd9/0x150 print_address_description.constprop.0+0x2c/0x3c0 kasan_report+0x11d/0x130 decode_session6+0x103f/0x1890 __xfrm_decode_session+0x54/0xb0 vti6_tnl_xmit+0x3e6/0x1ee0 dev_hard_start_xmit+0x187/0x700 sch_direct_xmit+0x1a3/0xc30 __qdisc_run+0x510/0x17a0 __dev_queue_xmit+0x2215/0x3b10 neigh_connected_output+0x3c2/0x550 ip6_finish_output2+0x55a/0x1550 ip6_finish_output+0x6b9/0x1270 ip6_output+0x1f1/0x540 ndisc_send_skb+0xa63/0x1890 ndisc_send_rs+0x132/0x6f0 addrconf_rs_timer+0x3f1/0x870 call_timer_fn+0x1a0/0x580 expire_timers+0x29b/0x4b0 run_timer_softirq+0x326/0x910 __do_softirq+0x1d4/0x905 irq_exit_rcu+0xb7/0x120 sysvec_apic_timer_interrupt+0x97/0xc0 </IRQ> Allocated by task 9176: kasan_save_stack+0x22/0x40 kasan_set_track+0x25/0x30 __kasan_slab_alloc+0x7f/0x90 kmem_cache_alloc_node+0x1cd/0x410 kmalloc_reserve+0x165/0x270 __alloc_skb+0x129/0x330 netlink_sendmsg+0x9b1/0xe30 sock_sendmsg+0xde/0x190 ____sys_sendmsg+0x739/0x920 ___sys_sendmsg+0x110/0x1b0 __sys_sendmsg+0xf7/0x1c0 do_syscall_64+0x39/0xb0 entry_SYSCALL_64_after_hwframe+0x63/0xcd Freed by task 9176: kasan_save_stack+0x22/0x40 kasan_set_track+0x25/0x30 kasan_save_free_info+0x2b/0x40 ____kasan_slab_free+0x160/0x1c0 slab_free_freelist_hook+0x11b/0x220 kmem_cache_free+0xf0/0x490 skb_free_head+0x17f/0x1b0 skb_release_data+0x59c/0x850 consume_skb+0xd2/0x170 netlink_unicast+0x54f/0x7f0 netlink_sendmsg+0x926/0xe30 sock_sendmsg+0xde/0x190 ____sys_sendmsg+0x739/0x920 ___sys_sendmsg+0x110/0x1b0 __sys_sendmsg+0xf7/0x1c0 do_syscall_64+0x39/0xb0 entry_SYSCALL_64_after_hwframe+0x63/0xcd The buggy address belongs to the object at ffff88802e08ed00 which belongs to the cache skbuff_small_head of size 640 The buggy address is located 194 bytes inside of freed 640-byte region [ffff88802e08ed00, ffff88802e08ef80) As commit f855691975bb ("xfrm6: Fix the nexthdr offset in _decode_session6.") showed, xfrm_decode_session was originally intended only for the receive path. IP6CB(skb)->nhoff is not set during transmission. Therefore, set the cb field in the skb to 0 before sending packets.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于ip6_vti设备在发送IPv6包时可能触发释放后重用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux f855691975bb06373a98711e4cfe2c224244b536 ~ 0f0ab8d52ee0062b28367dea23c29e254a26d7db -
Linux Linux 3.19 -

II. Public POCs for CVE-2023-53821

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III. Intelligence Information for CVE-2023-53821

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Same Patch Batch · Linux · 2025-12-09 · 152 CVEs total

CVE-2025-40343 9.8 CRITICAL nvmet-fc: avoid scheduling association deletion twice
CVE-2023-53794 9.8 CRITICAL cifs: fix session state check in reconnect to avoid use-after-free issue
CVE-2022-50666 9.8 CRITICAL RDMA/siw: Fix QP destroy to wait for all references dropped.
CVE-2023-53827 8.8 HIGH Bluetooth: L2CAP: Fix use-after-free in l2cap_disconnect_{req,rsp}
CVE-2023-53785 8.8 HIGH mt76: mt7921: don't assume adequate headroom for SDIO headers
CVE-2023-53822 8.8 HIGH wifi: ath11k: Ignore frags from uninitialized peer in dp.
CVE-2025-40336 8.8 HIGH drm/gpusvm: fix hmm_pfn_to_map_order() usage
CVE-2025-40342 8.8 HIGH nvme-fc: use lock accessing port_state and rport state
CVE-2025-40328 8.8 HIGH smb: client: fix potential UAF in smb2_close_cached_fid()
CVE-2023-53851 8.4 HIGH drm/msm/dp: Drop aux devices together with DP controller
CVE-2025-40337 8.2 HIGH net: stmmac: Correctly handle Rx checksum offload errors
CVE-2022-50656 8.1 HIGH nfc: pn533: Clear nfc_target before being used
CVE-2023-53803 8.1 HIGH scsi: ses: Fix slab-out-of-bounds in ses_enclosure_data_process()
CVE-2023-53804 7.8 HIGH nilfs2: fix use-after-free bug of nilfs_root in nilfs_evict_inode()
CVE-2023-53819 7.8 HIGH amdgpu: validate offset_in_bo of drm_amdgpu_gem_va
CVE-2023-53816 7.8 HIGH drm/amdkfd: fix potential kgd_mem UAFs
CVE-2023-53800 7.8 HIGH ubi: Fix use-after-free when volume resizing failed
CVE-2023-53790 7.8 HIGH bpf: Zeroing allocated object from slab in bpf memory allocator
CVE-2023-53795 7.8 HIGH iommufd: IOMMUFD_DESTROY should not increase the refcount
CVE-2023-53810 7.8 HIGH blk-mq: release crypto keyslot before reporting I/O complete

Showing top 20 of 152 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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