CVE-2023-53821

NONECVSS 0.0
0.0
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • No confirmed exploitation signals yet
CISA-KEV: Not listedEPSS: 0%CVSS: —Exploit: NoneExposed: 0

A fix is available — apply it.

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:

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

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.

CVSS v3
—
EG Score
0.0(none)
EG Risk
—
EPSS
13.2%
KEV
Not listed

Published

December 9, 2025

Last Modified

April 15, 2026

References (8)

Vendor Advisories for CVE-2023-53821(10)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(11)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatkernel-0:4.18.0-193.187.1.el8_22026-02-26redhat
redhatkernel-rt-0:5.14.0-70.167.1.rt21.239.el9_02026-02-25redhat
redhatkernel-0:4.18.0-477.130.1.el8_82026-02-25redhat
redhatkernel-0:5.14.0-284.158.1.el9_22026-02-25redhat
redhatkernel-rt-0:5.14.0-284.158.1.rt14.443.el9_22026-02-25redhat
redhatkernel-0:4.18.0-372.181.1.el8_62026-02-25redhat
redhatkernel-0:4.18.0-305.186.1.el8_42026-02-25redhat
redhatkernel-0:5.14.0-70.167.1.el9_02026-02-25redhat
redhatkernel-0:4.18.0-553.el8_102024-05-22redhat
redhatkernel-0:5.14.0-427.13.1.el9_42024-04-30redhat
linuxKernel @ 4.14.324—osv

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Data Freshness Timeline

(refreshed 12× in last 7d / 46× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 117 total refreshes for this CVE.

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Frequently asked(4)

What is CVE-2023-53821?
CVE-2023-53821 is a none vulnerability published on December 9, 2025. In the Linux kernel, the following vulnerability has been resolved: ip6vti: fix slab-use-after-free in decodesession6 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…
When was CVE-2023-53821 disclosed?
CVE-2023-53821 was first published in the National Vulnerability Database on December 9, 2025, with the most recent update on April 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2023-53821 actively exploited?
CVE-2023-53821 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 13.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
How do I remediate CVE-2023-53821?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2023-53821, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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