CVE-2023-53821

UNRATEDCVSS · not yet scoredTrending — 4 sources updated this week

Also known asEUVD-2023-60175 (ENISA EUVD) · GHSA-j65p-q5f6-5q5p (GitHub Security Advisories)Source: ENISA EUVD

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EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • No CVSS published and no exploitation signals yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS v2: —Exploit: None knownExposed services: Not assessed

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
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EchelonGraph score
Not yet assessedNo source has published severity data for this CVE yet — no CVSS score from NVD or a CNA, no GitHub advisory, and it is not in CISA KEV. This is not a rating of zero; we cannot assess it yet.
EG Score
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EG Risk
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EPSS PROB
0.3%
EPSS %ILE
17th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

EG Severity
Not assessed: no CVSS publishedA missing CVSS is not a severity of zero.
EG Likelihood
0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-26). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
No SSVC decision: EchelonGraph has not assessed this CVECISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the BOD 26-04 block below.

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

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 / EcosystemFix (by version range) / PatchReleasedSource
redhatkernel-0:4.18.0-193.187.1.el8_22026-02-26redhat
redhatkernel-0:4.18.0-477.130.1.el8_82026-02-25redhat
redhatkernel-0:5.14.0-70.167.1.el9_02026-02-25redhat
redhatkernel-rt-0:5.14.0-70.167.1.rt21.239.el9_02026-02-25redhat
redhatkernel-rt-0:5.14.0-284.158.1.rt14.443.el9_22026-02-25redhat
redhatkernel-0:4.18.0-305.186.1.el8_42026-02-25redhat
redhatkernel-0:4.18.0-372.181.1.el8_62026-02-25redhat
redhatkernel-0:5.14.0-284.158.1.el9_22026-02-25redhat
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 (fixes >=3.19.0)—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.

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
linux5.10.103-1 ... 5.10.92-2 (34 versions)
  • every version up to 5.10.197-1: fixed in 5.10.197-1
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Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.1.27-1 ... 6.1.38-4~bpo11+1 (8 versions)
  • every version up to 6.1.52-1: fixed in 6.1.52-1
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Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 6.4.13-1: fixed in 6.4.13-1
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Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 6.4.13-1: fixed in 6.4.13-1
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Data Freshness Timeline

(refreshed 10× in last 7d / 37× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 93 of 223 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 7 repeat rows among the latest 100 are merged into the row they repeat. The 130 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-01 16:31 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  2. 2026-10-31 16:30 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  3. 2026-10-30 16:31 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  4. 2026-10-29 16:30 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  5. 2026-10-28 16:29 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  6. 2026-10-27 16:29 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  7. 2026-10-27 10:42 UTCEG score recompute
  8. 2026-10-27 10:42 UTCVendor advisory
  9. 2026-10-27 10:42 UTCGHSA enrichmentGHSA-j65p-q5f6-5q5p
  10. 2026-10-26 16:29 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  11. 2026-10-25 17:27 UTCEG score recompute
  12. 2026-10-25 16:30 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  13. 2026-10-24 22:25 UTCOSV refresh
  14. 2026-10-24 16:29 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  15. 2026-10-23 16:29 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  16. 2026-10-21 16:29 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  17. 2026-10-20 16:30 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  18. 2026-10-19 16:29 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  19. 2026-10-18 16:29 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  20. 2026-10-18 07:40 UTCEG score recompute
  21. 2026-10-17 16:30 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  22. 2026-10-16 16:36 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  23. 2026-10-15 16:29 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  24. 2026-10-14 16:30 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  25. 2026-10-13 16:30 UTCEPSS rescoreEPSS 0.3% · 16th percentile
Show 68 more
  1. 2026-10-12 18:12 UTCEG score recompute
  2. 2026-10-12 16:31 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  3. 2026-10-11 21:37 UTCEG score recompute
  4. 2026-10-11 13:45 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  5. 2026-10-10 19:58 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  6. 2026-10-09 20:05 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  7. 2026-10-08 17:06 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  8. 2026-10-07 23:46 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  9. 2026-10-06 15:15 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  10. 2026-10-05 17:41 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  11. 2026-10-04 23:20 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  12. 2026-10-03 14:23 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  13. 2026-10-01 19:48 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  14. 2026-10-01 04:10 UTCOSV refresh
  15. 2026-09-30 16:38 UTCEG score recompute
  16. 2026-09-30 15:01 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  17. 2026-09-29 15:17 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  18. 2026-09-28 13:49 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  19. 2026-09-26 00:22 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  20. 2026-09-24 14:01 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  21. 2026-09-23 13:46 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  22. 2026-09-20 20:14 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  23. 2026-09-18 19:26 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  24. 2026-09-16 14:06 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  25. 2026-09-16 05:11 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  26. 2026-09-15 03:08 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  27. 2026-09-13 16:45 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  28. 2026-09-12 14:58 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  29. 2026-09-12 06:40 UTCOSV refresh
  30. 2026-09-11 14:51 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  31. 2026-09-11 09:34 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  32. 2026-09-08 21:58 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  33. 2026-09-07 15:59 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  34. 2026-09-06 13:46 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  35. 2026-09-05 15:26 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  36. 2026-09-04 13:58 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  37. 2026-09-02 14:10 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  38. 2026-09-01 13:52 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  39. 2026-09-01 04:36 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  40. 2026-08-30 19:15 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  41. 2026-08-30 01:20 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  42. 2026-08-28 21:39 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  43. 2026-08-27 14:23 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  44. 2026-08-26 14:44 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  45. 2026-08-25 13:47 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  46. 2026-08-24 12:00 UTCOSV refresh
  47. 2026-08-23 00:17 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  48. 2026-08-21 23:47 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  49. 2026-08-20 22:53 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  50. 2026-08-19 17:02 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  51. 2026-08-18 13:46 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  52. 2026-08-16 14:54 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  53. 2026-08-16 02:12 UTCEPSS rescoreEPSS 0.3% · 17th percentile
  54. 2026-08-15 01:28 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  55. 2026-08-13 21:58 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  56. 2026-08-12 13:49 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  57. 2026-08-11 13:40 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  58. 2026-08-10 23:58 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  59. 2026-08-09 13:44 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  60. 2026-08-08 16:35 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  61. 2026-08-08 08:02 UTCEG score recompute
  62. 2026-08-08 08:02 UTCVendor advisory
  63. 2026-08-08 08:02 UTCGHSA enrichmentGHSA-j65p-q5f6-5q5p
  64. 2026-08-07 16:25 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  65. 2026-08-06 13:45 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  66. 2026-08-05 19:15 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  67. 2026-08-04 10:36 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  68. 2026-08-03 10:34 UTCEPSS rescoreEPSS 0.2% · 13th percentile

Related CVEs(same vendor)

Frequently asked(4)

What is CVE-2023-53821?
CVE-2023-53821 is a vulnerability whose severity is not yet rated; its CVE record was published on December 9, 2025. 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…
When was the CVE record for CVE-2023-53821 published?
The CVE record for CVE-2023-53821 was published on December 9, 2025. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of April 15, 2026; the record at its source may have been updated since.
Is CVE-2023-53821 actively exploited?
CVE-2023-53821 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (17th percentile of EPSS-scored CVEs).
How do I remediate CVE-2023-53821?
A fix for CVE-2023-53821 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2023-53821 are linked in the Vendor Advisories panel on this page.

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