CVE-2023-53500

HIGHNVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2025-10-01. NVD baseline CVSS 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this week
7.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.8Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

In the Linux kernel, the following vulnerability has been resolved:

xfrm: fix slab-use-after-free in decode_session6

When the xfrm 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 the xfrm 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 ffff8881111458ef by task swapper/3/0 CPU: 3 PID: 0 Comm: swapper/3 Not tainted 6.4.0-next-20230707 #409 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 xfrmi_xmit+0x173/0x1ca0 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

asm_sysvec_apic_timer_interrupt+0x1a/0x20 RIP: 0010:intel_idle_hlt+0x23/0x30 Code: 1f 84 00 00 00 00 00 f3 0f 1e fa 41 54 41 89 d4 0f 1f 44 00 00 66 90 0f 1f 44 00 00 0f 00 2d c4 9f ab 00 0f 1f 44 00 00 fb f4 44 89 e0 41 5c c3 66 0f 1f 44 00 00 f3 0f 1e fa 41 54 41 89 d4 RSP: 0018:ffffc90000197d78 EFLAGS: 00000246 RAX: 00000000000a83c3 RBX: ffffe8ffffd09c50 RCX: ffffffff8a22d8e5 RDX: 0000000000000001 RSI: ffffffff8d3f8080 RDI: ffffe8ffffd09c50 RBP: ffffffff8d3f8080 R08: 0000000000000001 R09: ffffed1026ba6d9d R10: ffff888135d36ceb R11: 0000000000000001 R12: 0000000000000001 R13: ffffffff8d3f8100 R14: 0000000000000001 R15: 0000000000000000 cpuidle_enter_state+0xd3/0x6f0 cpuidle_enter+0x4e/0xa0 do_idle+0x2fe/0x3c0 cpu_startup_entry+0x18/0x20 start_secondary+0x200/0x290 secondary_startup_64_no_verify+0x167/0x16b

Allocated by task 939: 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 inet6_ifa_notify+0x118/0x230 __ipv6_ifa_notify+0x177/0xbe0 addrconf_dad_completed+0x133/0xe00 addrconf_dad_work+0x764/0x1390 process_one_work+0xa32/0x16f0 worker_thread+0x67d/0x10c0 kthread+0x344/0x440 ret_from_fork+0x1f/0x30 The buggy address belongs to the object at ffff888111145800 which belongs to the cache skbuff_small_head of size 640 The buggy address is located 239 bytes inside of freed 640-byte region [ffff888111145800, ffff888111145a80)

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
7.8
EG Score
7.8(medium)
EG Risk
40(Track)
EG Risk 40/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity78% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
5%
KEV
Not listed

Published

October 1, 2025

Last Modified

August 5, 2026

Advisory Details (7)

Auto-updated Aug 5, 2026
No patch confirmed yet.
generic

xfrm: fix slab-use-after-free in decode_session6 - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/53223f2ed1ef5c90dad814daaaefea4e68a933c8
generic

xfrm: fix slab-use-after-free in decode_session6 - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/86f15300a22656db3fa8c8967defbcd24fac4d37
generic

xfrm: fix slab-use-after-free in decode_session6 - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/0d27567fde5be5f0edc2db5c110142b7915b8fa8
generic

xfrm: fix slab-use-after-free in decode_session6 - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/44b3d40967009304617a7a6486490c1d6c12f899
generic

xfrm: fix slab-use-after-free in decode_session6 - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/bafa236380816b41b2c4c6970d9067fefa4a6c9e
generic

xfrm: fix slab-use-after-free in decode_session6 - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/db0e50741f0387f388e9ec824ea7ae8456554d5b
generic

xfrm: fix slab-use-after-free in decode_session6 - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/da4cbaa75ed088b6d70db77b9103a27e2359e243

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
linuxKernel @ 4.19.293—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.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 15× in last 7d / 48× 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 112 total refreshes for this CVE.

  1. 2026-08-05 19:15 UTCEPSS rescore
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Frequently asked(5)

What is CVE-2023-53500?
CVE-2023-53500 is a high vulnerability published on October 1, 2025. In the Linux kernel, the following vulnerability has been resolved: xfrm: fix slab-use-after-free in decode_session6 When the xfrm 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 the xfrm device…
When was CVE-2023-53500 disclosed?
CVE-2023-53500 was first published in the National Vulnerability Database on October 1, 2025, with the most recent update on August 5, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2023-53500 actively exploited?
CVE-2023-53500 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 95.3% of all scored CVEs.
What is the CVSS score of CVE-2023-53500?
CVE-2023-53500 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2023-53500?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2023-53500, 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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