CVE-2021-47222

HIGHNVD 7.87.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2024-05-21. NVD baseline CVSS 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 3 sources updated this week

Also known asEUVD-2021-33870 (ENISA EUVD) · GHSA-h423-6g7m-qpqq (GitHub Security Advisories)Source: ENISA EUVD

7.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 7.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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

net: bridge: fix vlan tunnel dst refcnt when egressing

The egress tunnel code uses dst_clone() and directly sets the result which is wrong because the entry might have 0 refcnt or be already deleted, causing number of problems. It also triggers the WARN_ON() in dst_hold()[1] when a refcnt couldn't be taken. Fix it by using dst_hold_safe() and checking if a reference was actually taken before setting the dst.

[1] dmesg WARN_ON log and following refcnt errors WARNING: CPU: 5 PID: 38 at include/net/dst.h:230 br_handle_egress_vlan_tunnel+0x10b/0x134 [bridge] Modules linked in: 8021q garp mrp bridge stp llc bonding ipv6 virtio_net CPU: 5 PID: 38 Comm: ksoftirqd/5 Kdump: loaded Tainted: G W 5.13.0-rc3+ #360 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33 04/01/2014 RIP: 0010:br_handle_egress_vlan_tunnel+0x10b/0x134 [bridge] Code: e8 85 bc 01 e1 45 84 f6 74 90 45 31 f6 85 db 48 c7 c7 a0 02 19 a0 41 0f 94 c6 31 c9 31 d2 44 89 f6 e8 64 bc 01 e1 85 db 75 02 <0f> 0b 31 c9 31 d2 44 89 f6 48 c7 c7 70 02 19 a0 e8 4b bc 01 e1 49 RSP: 0018:ffff8881003d39e8 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffffa01902a0 RBP: ffff8881040c6700 R08: 0000000000000000 R09: 0000000000000001 R10: 2ce93d0054fe0d00 R11: 54fe0d00000e0000 R12: ffff888109515000 R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000401 FS: 0000000000000000(0000) GS:ffff88822bf40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f42ba70f030 CR3: 0000000109926000 CR4: 00000000000006e0 Call Trace: br_handle_vlan+0xbc/0xca [bridge] __br_forward+0x23/0x164 [bridge] deliver_clone+0x41/0x48 [bridge] br_handle_frame_finish+0x36f/0x3aa [bridge] ? skb_dst+0x2e/0x38 [bridge] ? br_handle_ingress_vlan_tunnel+0x3e/0x1c8 [bridge] ? br_handle_frame_finish+0x3aa/0x3aa [bridge] br_handle_frame+0x2c3/0x377 [bridge] ? __skb_pull+0x33/0x51 ? vlan_do_receive+0x4f/0x36a ? br_handle_frame_finish+0x3aa/0x3aa [bridge] __netif_receive_skb_core+0x539/0x7c6 ? __list_del_entry_valid+0x16e/0x1c2 __netif_receive_skb_list_core+0x6d/0xd6 netif_receive_skb_list_internal+0x1d9/0x1fa gro_normal_list+0x22/0x3e dev_gro_receive+0x55b/0x600 ? detach_buf_split+0x58/0x140 napi_gro_receive+0x94/0x12e virtnet_poll+0x15d/0x315 [virtio_net] __napi_poll+0x2c/0x1c9 net_rx_action+0xe6/0x1fb __do_softirq+0x115/0x2d8 run_ksoftirqd+0x18/0x20 smpboot_thread_fn+0x183/0x19c ? smpboot_unregister_percpu_thread+0x66/0x66 kthread+0x10a/0x10f ? kthread_mod_delayed_work+0xb6/0xb6 ret_from_fork+0x22/0x30 ---[ end trace 49f61b07f775fd2b ]--- dst_release: dst:00000000c02d677a refcnt:-1 dst_release underflow

CVSS v3
7.8
EG Score
7.8HIGHmedium confidence
EG Risk
35
EG Risk 35/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity78% × 45%
Impact severity (EG Severity): CVSS 7.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.2% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.2%
EPSS %ILE
16th
KEV
Not listed

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

The EG score (7.8): severity, escalated by confirmed exploitation. This CVE's 7.8 is its impact severity (EG Severity), not escalated.

EG Severity
7.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-27). 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
SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 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 SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 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 Vulnrichment) · Technical impact partial (CISA Vulnrichment). 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

May 21, 2024

Last Modified

August 5, 2026

Advisory Details (6)

Auto-updated Aug 4, 2026
Patch available.
Web page

net: bridge: fix vlan tunnel dst refcnt when egressing - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/84fc1c944e45ab317e2e70a0e7f76fa2a5e43b6e
Web page

net: bridge: fix vlan tunnel dst refcnt when egressing - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/79855be6445b6592bddb7bd7167083ec8cdbd73f
Web page

net: bridge: fix vlan tunnel dst refcnt when egressing - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/42020f7f37a90d24b9551f5f7eba3f7c7c102968
Web page

net: bridge: fix vlan tunnel dst refcnt when egressing - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/25053a8404ba17ca48f5553d487afc1882e9f56c
Web page

net: bridge: fix vlan tunnel dst refcnt when egressing - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/fc7fdd8c5c2ad2fe3e297698be9d4dbe4a4e0579
Web page

net: bridge: fix vlan tunnel dst refcnt when egressing - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/cfc579f9d89af4ada58c69b03bcaa4887840f3b3

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 5.10.46-1: fixed in 5.10.46-1
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 5.10.46-1: fixed in 5.10.46-1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 5.10.46-1: fixed in 5.10.46-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 5.10.46-1: fixed in 5.10.46-1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 39× 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 97 of 212 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. 3 repeat rows among the latest 100 are merged into the row they repeat. The 115 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-02 16:38 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  2. 2026-11-01 16:30 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  3. 2026-10-31 16:29 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  4. 2026-10-30 16:30 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  5. 2026-10-29 16:29 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  6. 2026-10-28 16:28 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  7. 2026-10-28 15:48 UTCEG score recompute
  8. 2026-10-28 15:48 UTCGHSA enrichmentGHSA-h423-6g7m-qpqq · GitHub severity HIGH · GitHub CVSS 7.8
  9. 2026-10-27 16:28 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  10. 2026-10-26 16:28 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  11. 2026-10-25 18:18 UTCEG score recompute
  12. 2026-10-25 16:29 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  13. 2026-10-24 16:29 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  14. 2026-10-23 16:28 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  15. 2026-10-22 16:29 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  16. 2026-10-21 16:28 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  17. 2026-10-21 08:34 UTCEG score recompute
  18. 2026-10-21 08:34 UTCGHSA enrichmentGHSA-h423-6g7m-qpqq · GitHub severity HIGH · GitHub CVSS 7.8
  19. 2026-10-20 16:28 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  20. 2026-10-19 16:28 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  21. 2026-10-19 13:25 UTCOSV refresh
  22. 2026-10-18 16:28 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  23. 2026-10-18 08:49 UTCEG score recompute
  24. 2026-10-17 16:29 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  25. 2026-10-16 16:34 UTCEPSS rescoreEPSS 0.2% · 14th percentile
Show 72 more
  1. 2026-10-15 16:28 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  2. 2026-10-14 16:29 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  3. 2026-10-13 16:28 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  4. 2026-10-12 19:05 UTCEG score recompute
  5. 2026-10-12 16:30 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  6. 2026-10-11 23:31 UTCEG score recompute
  7. 2026-10-11 13:44 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  8. 2026-10-10 19:56 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  9. 2026-10-09 20:04 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  10. 2026-10-08 16:40 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  11. 2026-10-07 23:45 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  12. 2026-10-06 15:14 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  13. 2026-10-05 17:40 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  14. 2026-10-04 23:19 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  15. 2026-10-03 14:22 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  16. 2026-10-02 16:23 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  17. 2026-09-30 15:45 UTCEG score recompute
  18. 2026-09-30 15:00 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  19. 2026-09-29 15:15 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  20. 2026-09-28 13:47 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  21. 2026-09-26 20:03 UTCOSV refresh
  22. 2026-09-26 15:54 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  23. 2026-09-26 00:21 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  24. 2026-09-24 14:00 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  25. 2026-09-23 13:45 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  26. 2026-09-22 14:44 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  27. 2026-09-21 20:28 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  28. 2026-09-20 20:13 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  29. 2026-09-19 15:38 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  30. 2026-09-18 19:24 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  31. 2026-09-17 19:23 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  32. 2026-09-16 14:05 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  33. 2026-09-15 03:06 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  34. 2026-09-12 14:57 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  35. 2026-09-11 14:49 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  36. 2026-09-11 09:33 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  37. 2026-09-08 21:57 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  38. 2026-09-07 15:58 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  39. 2026-09-07 05:48 UTCOSV refresh
  40. 2026-09-06 13:45 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  41. 2026-09-05 15:25 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  42. 2026-09-04 13:57 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  43. 2026-09-04 05:03 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  44. 2026-09-02 14:09 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  45. 2026-09-01 13:51 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  46. 2026-08-30 19:14 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  47. 2026-08-30 01:19 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  48. 2026-08-28 21:38 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  49. 2026-08-27 14:22 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  50. 2026-08-26 14:43 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  51. 2026-08-25 13:46 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  52. 2026-08-24 14:13 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  53. 2026-08-21 23:46 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  54. 2026-08-20 22:52 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  55. 2026-08-20 15:31 UTCOSV refresh
  56. 2026-08-19 17:01 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  57. 2026-08-18 13:45 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  58. 2026-08-17 13:44 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  59. 2026-08-16 14:53 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  60. 2026-08-16 02:11 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  61. 2026-08-15 01:27 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  62. 2026-08-13 21:57 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  63. 2026-08-12 13:48 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  64. 2026-08-11 13:38 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  65. 2026-08-09 13:44 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  66. 2026-08-08 16:34 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  67. 2026-08-07 16:24 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  68. 2026-08-06 13:44 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  69. 2026-08-05 19:15 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  70. 2026-08-05 09:42 UTCEG score recompute
  71. 2026-08-05 09:42 UTCGHSA enrichmentGHSA-h423-6g7m-qpqq · GitHub severity HIGH · GitHub CVSS 7.8
  72. 2026-08-04 15:06 UTCEPSS rescoreEPSS 0.2% · 15th percentile

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-47222?
CVE-2021-47222 is a high-severity vulnerability; its CVE record was published on May 21, 2024. In the Linux kernel, the following vulnerability has been resolved: net: bridge: fix vlan tunnel dst refcnt when egressing The egress tunnel code uses dst_clone() and directly sets the result which is wrong because the entry might have 0 refcnt or be already deleted, causing number of problems. It…
When was the CVE record for CVE-2021-47222 published?
The CVE record for CVE-2021-47222 was published on May 21, 2024. 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 August 5, 2026; the record at its source may have been updated since.
Is CVE-2021-47222 actively exploited?
CVE-2021-47222 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (16th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2021-47222?
CVE-2021-47222 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2021-47222?
A fix for CVE-2021-47222 is available: update to the fixed version the vendor names in its advisory.

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