CVE-2021-47126

MEDIUMNVD 5.55.5
EchelonGraph scoreMEDIUM confidence

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

Score 5.5 from GitHub Security Advisory published 2024-03-15. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3

Also known asEUVD-2021-33774 (ENISA EUVD) · GHSA-q96w-v39p-hcjw (GitHub Security Advisories)Source: ENISA EUVD

5.5EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 5.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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

ipv6: Fix KASAN: slab-out-of-bounds Read in fib6_nh_flush_exceptions

Reported by syzbot: HEAD commit: 90c911ad Merge tag 'fixes' of git://git.kernel.org/pub/scm.. git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master dashboard link: https://syzkaller.appspot.com/bug?extid=123aa35098fd3c000eb7 compiler: Debian clang version 11.0.1-2

================================================================== BUG: KASAN: slab-out-of-bounds in fib6_nh_get_excptn_bucket net/ipv6/route.c:1604 [inline] BUG: KASAN: slab-out-of-bounds in fib6_nh_flush_exceptions+0xbd/0x360 net/ipv6/route.c:1732 Read of size 8 at addr ffff8880145c78f8 by task syz-executor.4/17760

CPU: 0 PID: 17760 Comm: syz-executor.4 Not tainted 5.12.0-rc8-syzkaller #0 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x202/0x31e lib/dump_stack.c:120 print_address_description+0x5f/0x3b0 mm/kasan/report.c:232 __kasan_report mm/kasan/report.c:399 [inline] kasan_report+0x15c/0x200 mm/kasan/report.c:416 fib6_nh_get_excptn_bucket net/ipv6/route.c:1604 [inline] fib6_nh_flush_exceptions+0xbd/0x360 net/ipv6/route.c:1732 fib6_nh_release+0x9a/0x430 net/ipv6/route.c:3536 fib6_info_destroy_rcu+0xcb/0x1c0 net/ipv6/ip6_fib.c:174 rcu_do_batch kernel/rcu/tree.c:2559 [inline] rcu_core+0x8f6/0x1450 kernel/rcu/tree.c:2794 __do_softirq+0x372/0x7a6 kernel/softirq.c:345 invoke_softirq kernel/softirq.c:221 [inline] __irq_exit_rcu+0x22c/0x260 kernel/softirq.c:422 irq_exit_rcu+0x5/0x20 kernel/softirq.c:434 sysvec_apic_timer_interrupt+0x91/0xb0 arch/x86/kernel/apic/apic.c:1100 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:632 RIP: 0010:lock_acquire+0x1f6/0x720 kernel/locking/lockdep.c:5515 Code: f6 84 24 a1 00 00 00 02 0f 85 8d 02 00 00 f7 c3 00 02 00 00 49 bd 00 00 00 00 00 fc ff df 74 01 fb 48 c7 44 24 40 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 4b c7 44 3d 09 00 00 00 00 43 c7 44 3d RSP: 0018:ffffc90009e06560 EFLAGS: 00000206 RAX: 1ffff920013c0cc0 RBX: 0000000000000246 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90009e066e0 R08: dffffc0000000000 R09: fffffbfff1f992b1 R10: fffffbfff1f992b1 R11: 0000000000000000 R12: 0000000000000000 R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffff920013c0cb4 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:267 rcu_read_lock include/linux/rcupdate.h:656 [inline] ext4_get_group_info+0xea/0x340 fs/ext4/ext4.h:3231 ext4_mb_prefetch+0x123/0x5d0 fs/ext4/mballoc.c:2212 ext4_mb_regular_allocator+0x8a5/0x28f0 fs/ext4/mballoc.c:2379 ext4_mb_new_blocks+0xc6e/0x24f0 fs/ext4/mballoc.c:4982 ext4_ext_map_blocks+0x2be3/0x7210 fs/ext4/extents.c:4238 ext4_map_blocks+0xab3/0x1cb0 fs/ext4/inode.c:638 ext4_getblk+0x187/0x6c0 fs/ext4/inode.c:848 ext4_bread+0x2a/0x1c0 fs/ext4/inode.c:900 ext4_append+0x1a4/0x360 fs/ext4/namei.c:67 ext4_init_new_dir+0x337/0xa10 fs/ext4/namei.c:2768 ext4_mkdir+0x4b8/0xc00 fs/ext4/namei.c:2814 vfs_mkdir+0x45b/0x640 fs/namei.c:3819 ovl_do_mkdir fs/overlayfs/overlayfs.h:161 [inline] ovl_mkdir_real+0x53/0x1a0 fs/overlayfs/dir.c:146 ovl_create_real+0x280/0x490 fs/overlayfs/dir.c:193 ovl_workdir_create+0x425/0x600 fs/overlayfs/super.c:788 ovl_make_workdir+0xed/0x1140 fs/overlayfs/super.c:1355 ovl_get_workdir fs/overlayfs/super.c:1492 [inline] ovl_fill_super+0x39ee/0x5370 fs/overlayfs/super.c:2035 mount_nodev+0x52/0xe0 fs/super.c:1413 legacy_get_tree+0xea/0x180 fs/fs_context.c:592 vfs_get_tree+0x86/0x270 fs/super.c:1497 do_new_mount fs/namespace.c:2903 [inline] path_mount+0x196f/0x2be0 fs/namespace.c:3233 do_mount fs/namespace.c:3246 [inline] __do_sys_mount fs/namespace.c:3454 [inline] __se_sys_mount+0x2f9/0x3b0 fs/namespace.c:3431 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665f9 Code: ff ff c3 66 2e 0f 1f 84 ---truncated---

CVSS v3
5.5
EG Score
5.5MEDIUMmedium confidence
EG Risk
25
EG Risk 25/100

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)
Severity55% × 45%
Impact severity (EG Severity): CVSS 5.5 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 (5.5): severity, escalated by confirmed exploitation. This CVE's 5.5 is its impact severity (EG Severity), not escalated.

EG Severity
5.5 MEDIUMCVSS-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 2026-10-25). 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

March 15, 2024

Last Modified

August 5, 2026

References (4)

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 6× in last 7d / 36× 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 210 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 113 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. 2026-10-30 16:30 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  4. 2026-10-29 16:29 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  5. 2026-10-28 16:28 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  6. 2026-10-27 16:28 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  7. 2026-10-26 16:28 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  8. 2026-10-25 18:18 UTCEG score recompute
  9. 2026-10-25 16:29 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  10. 2026-10-24 21:49 UTCEG score recompute
  11. 2026-10-24 21:49 UTCGHSA enrichmentGHSA-q96w-v39p-hcjw · GitHub CVSS 5.5
  12. 2026-10-24 16:29 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  13. 2026-10-23 16:28 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  14. 2026-10-22 16:29 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  15. 2026-10-21 16:28 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  16. 2026-10-20 16:28 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  17. 2026-10-19 16:28 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  18. 2026-10-19 12:55 UTCOSV refresh
  19. 2026-10-18 16:28 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  20. 2026-10-18 08:49 UTCEG score recompute
  21. 2026-10-17 16:29 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  22. 2026-10-16 16:34 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  23. 2026-10-15 16:28 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  24. 2026-10-14 16:29 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  25. 2026-10-13 16:28 UTCEPSS rescoreEPSS 0.2% · 14th percentile
Show 72 more
  1. 2026-10-12 19:05 UTCEG score recompute
  2. 2026-10-12 16:30 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  3. 2026-10-11 23:31 UTCEG score recompute
  4. 2026-10-11 13:44 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  5. 2026-10-10 19:56 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  6. 2026-10-09 20:04 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  7. 2026-10-08 16:40 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  8. 2026-10-07 23:45 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  9. 2026-10-06 15:14 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  10. 2026-10-05 17:40 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  11. 2026-10-04 23:19 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  12. 2026-10-03 14:22 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  13. 2026-10-02 16:23 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  14. 2026-09-30 15:45 UTCEG score recompute
  15. 2026-09-30 15:00 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  16. 2026-09-29 15:15 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  17. 2026-09-28 13:47 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  18. 2026-09-26 20:03 UTCOSV refresh
  19. 2026-09-26 15:54 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  20. 2026-09-26 00:21 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  21. 2026-09-24 14:00 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  22. 2026-09-23 13:45 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  23. 2026-09-22 14:44 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  24. 2026-09-21 20:28 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  25. 2026-09-20 20:13 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  26. 2026-09-19 15:38 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  27. 2026-09-18 19:24 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  28. 2026-09-17 19:23 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  29. 2026-09-16 14:05 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  30. 2026-09-15 03:06 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  31. 2026-09-12 14:57 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  32. 2026-09-11 14:49 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  33. 2026-09-11 09:33 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  34. 2026-09-08 21:57 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  35. 2026-09-07 15:58 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  36. 2026-09-07 05:48 UTCOSV refresh
  37. 2026-09-06 13:45 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  38. 2026-09-05 15:25 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  39. 2026-09-04 13:57 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  40. 2026-09-04 05:03 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  41. 2026-09-02 14:09 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  42. 2026-09-01 13:51 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  43. 2026-08-30 19:14 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  44. 2026-08-30 01:19 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  45. 2026-08-28 21:38 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  46. 2026-08-27 14:22 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  47. 2026-08-26 14:43 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  48. 2026-08-25 13:46 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  49. 2026-08-24 14:13 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  50. 2026-08-21 23:46 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  51. 2026-08-20 22:52 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  52. 2026-08-20 15:31 UTCOSV refresh
  53. 2026-08-19 17:01 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  54. 2026-08-18 13:45 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  55. 2026-08-17 13:44 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  56. 2026-08-16 14:53 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  57. 2026-08-16 02:11 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  58. 2026-08-15 01:27 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  59. 2026-08-13 21:57 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  60. 2026-08-12 13:48 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  61. 2026-08-11 13:38 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  62. 2026-08-09 13:44 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  63. 2026-08-08 16:34 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  64. 2026-08-07 16:24 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  65. 2026-08-05 19:15 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  66. 2026-08-05 09:43 UTCEG score recompute
  67. 2026-08-05 09:43 UTCGHSA enrichmentGHSA-q96w-v39p-hcjw · GitHub CVSS 5.5
  68. 2026-08-04 15:06 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  69. 2026-08-04 12:20 UTCEG score recompute
  70. 2026-08-04 12:20 UTCGHSA enrichmentGHSA-q96w-v39p-hcjw · GitHub CVSS 5.5
  71. 2026-08-04 10:34 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  72. 2026-08-04 09:53 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-47126?
CVE-2021-47126 is a medium-severity vulnerability; its CVE record was published on March 15, 2024. In the Linux kernel, the following vulnerability has been resolved: ipv6: Fix KASAN: slab-out-of-bounds Read in fib6_nh_flush_exceptions Reported by syzbot: HEAD commit: 90c911ad Merge tag 'fixes' of git://git.kernel.org/pub/scm.. git tree:…
When was the CVE record for CVE-2021-47126 published?
The CVE record for CVE-2021-47126 was published on March 15, 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-2021-47126 actively exploited?
CVE-2021-47126 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-2021-47126?
CVE-2021-47126 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2021-47126?
A fix for CVE-2021-47126 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-47126

Explore →

Is Your Infrastructure Affected by CVE-2021-47126?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Book a Demo →Browse All CVEs