CVE-2021-20322

HIGHNVD 7.47.4—
EchelonGraph scoreMEDIUM confidence

Score 7.4 from GitHub Security Advisory (severity: CRITICAL) published 2022-02-19. NVD baseline CVSS 7.4; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
7.4EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 7%CVSS: 7.4Exploit: None knownExposed: 0

A fix is available — apply it.

A flaw in the processing of received ICMP errors (ICMP fragment needed and ICMP redirect) in the Linux kernel functionality was found to allow the ability to quickly scan open UDP ports. This flaw allows an off-path remote user to effectively bypass the source port UDP randomization. The highest threat from this vulnerability is to confidentiality and possibly integrity, because software that relies on UDP source port randomization are indirectly affected as well.

CVSS v3
7.4
EG Score
7.4(medium)
EG Risk
41(Track)
EG Risk 41/100SSVC: 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
Severity74% × 45%
Exploitation7% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
7%
EPSS %ILE
94%
KEV
Not listed

Published

February 18, 2022

Last Modified

July 30, 2026

Advisory Details (8)

Auto-updated Jul 30, 2026
Patch available. Sources: redhat.
generic

NetApp Product Security

https://security.netapp.com/advisory/ntap-20220303-0002/
generic Patch Available

[SECURITY] [DSA 5096-1] linux security update

https://www.debian.org/security/2022/dsa-5096
generic Patch Available

[SECURITY] [DLA 2941-1] linux-4.19 security update

https://lists.debian.org/debian-lts-announce/2022/03/msg00012.html
generic

ipv6: make exception cache less predictible - kernel/git/torvalds/linux.git - Linux kernel source tree

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/ipv6/route.c?h=v5.15-rc6&id=a00df2caffed3883c341d5685f830434312e4a43
generic

ipv4: make exception cache less predictible - kernel/git/torvalds/linux.git - Linux kernel source tree

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/ipv4/route.c?h=v5.15-rc6&id=67d6d681e15b578c1725bad8ad079e05d1c48a8e
generic

ipv4: use siphash instead of Jenkins in fnhe_hashfun() - kernel/git/torvalds/linux.git - Linux kernel source tree

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.15-rc6&id=6457378fe796815c973f631a1904e147d6ee33b1
generic

ipv6: use siphash in rt6_exception_hash() - kernel/git/torvalds/linux.git - Linux kernel source tree

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.15-rc6&id=4785305c05b25a242e5314cc821f54ade4c18810
redhat Patch Available

2014230 – (CVE-2021-20322) CVE-2021-20322 kernel: new DNS Cache Poisoning Attack based on ICMP fragment needed packets replies

Affected: Red Hat Enterprise Linux 8

https://bugzilla.redhat.com/show_bug.cgi?id=2014230

Vendor Advisories for CVE-2021-20322(5)

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

Patch Availability(5)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-tools-azure (4.15.0.1130.103) @ trusty2026-05-26ubuntu
redhatkernel-0:4.18.0-305.49.1.el8_42022-05-31redhat
redhatkernel-rt-0:4.18.0-305.49.1.rt7.121.el8_42022-05-31redhat
redhatkernel-rt-0:4.18.0-372.9.1.rt7.166.el82022-05-10redhat
redhatkernel-0:4.18.0-372.9.1.el82022-05-10redhat

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

(7 across 6 ecosystems)
Debian:9(2)
PackageVulnerable rangeFixed inDependents
linux4.9.107-1 ... 4.9.88-1~bpo8+1 (68 versions)4.9.290-1—
linux-4.194.19.132-1~deb9u1 ... 4.19.208-1~deb9u1 (10 versions)4.19.232-1~deb9u1—
Debian:10(1)
PackageVulnerable rangeFixed inDependents
linux4.19.118-1 ... 4.19.98-1~bpo9+1 (36 versions)4.19.232-1—
Debian:11(1)
PackageVulnerable rangeFixed inDependents
linux5.10.46-4, 5.10.46-5, 5.10.70-1~bpo10+15.10.70-1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
linux—5.14.6-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
linux—5.14.6-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux—5.14.6-1—

Weakness Classification(1)

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

Additional Vendor Advisories

(2)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 7× in last 7d / 28× 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 151 total refreshes for this CVE.

  1. 2026-09-07 15:58 UTCEPSS rescore
  2. 2026-09-06 13:44 UTCEPSS rescore
  3. 2026-09-06 13:44 UTCEPSS rescore
  4. 2026-09-05 15:25 UTCEPSS rescore
  5. 2026-09-04 13:57 UTCEPSS rescore
  6. 2026-09-04 05:03 UTCEPSS rescore
  7. 2026-09-02 14:08 UTCEPSS rescore
  8. 2026-09-01 13:50 UTCEPSS rescore
  9. 2026-09-01 08:59 UTCOSV refresh
  10. 2026-09-01 03:32 UTCEPSS rescore
  11. 2026-08-30 19:14 UTCEPSS rescore
  12. 2026-08-30 01:19 UTCEPSS rescore
  13. 2026-08-28 21:37 UTCEPSS rescore
  14. 2026-08-27 14:22 UTCEPSS rescore
  15. 2026-08-26 14:42 UTCEPSS rescore
  16. 2026-08-25 13:45 UTCEPSS rescore
  17. 2026-08-23 00:16 UTCEPSS rescore
  18. 2026-08-21 23:46 UTCEPSS rescore
  19. 2026-08-20 22:52 UTCEPSS rescore
  20. 2026-08-19 17:01 UTCEPSS rescore
  21. 2026-08-18 13:45 UTCEPSS rescore
  22. 2026-08-16 14:52 UTCEPSS rescore
  23. 2026-08-16 02:11 UTCEPSS rescore
  24. 2026-08-15 08:37 UTCOSV refresh
  25. 2026-08-15 01:27 UTCEPSS rescore
Show 75 more
  1. 2026-08-13 21:57 UTCEPSS rescore
  2. 2026-08-12 13:47 UTCEPSS rescore
  3. 2026-08-11 13:38 UTCEPSS rescore
  4. 2026-08-08 16:33 UTCEPSS rescore
  5. 2026-08-07 16:23 UTCEPSS rescore
  6. 2026-08-06 13:43 UTCEPSS rescore
  7. 2026-08-05 19:14 UTCEPSS rescore
  8. 2026-08-04 15:06 UTCEPSS rescore
  9. 2026-08-04 10:34 UTCEPSS rescore
  10. 2026-08-03 10:32 UTCEPSS rescore
  11. 2026-08-02 02:24 UTCEPSS rescore
  12. 2026-08-01 04:12 UTCEPSS rescore
  13. 2026-07-30 20:25 UTCEG score recompute
  14. 2026-07-30 20:25 UTCVendor advisory
  15. 2026-07-30 20:25 UTCGHSA enrichment
  16. 2026-07-30 16:25 UTCEPSS rescore
  17. 2026-07-30 16:23 UTCVendor advisory
  18. 2026-07-30 16:23 UTCGHSA enrichment
  19. 2026-07-30 16:13 UTCEG score recompute
  20. 2026-07-30 16:13 UTCVendor advisory
  21. 2026-07-30 16:13 UTCGHSA enrichment
  22. 2026-07-30 01:27 UTCEPSS rescore
  23. 2026-07-30 01:27 UTCEPSS rescore
  24. 2026-07-25 14:15 UTCEPSS rescore
  25. 2026-07-24 14:15 UTCEPSS rescore
  26. 2026-07-23 14:15 UTCEPSS rescore
  27. 2026-07-23 01:56 UTCEG score recompute
  28. 2026-07-22 22:43 UTCEG score recompute
  29. 2026-07-22 14:05 UTCEPSS rescore
  30. 2026-07-21 15:22 UTCEPSS rescore
  31. 2026-07-21 15:22 UTCEPSS rescore
  32. 2026-07-20 17:04 UTCEPSS rescore
  33. 2026-07-19 14:28 UTCEPSS rescore
  34. 2026-07-19 02:26 UTCEPSS rescore
  35. 2026-07-18 10:02 UTCEPSS rescore
  36. 2026-07-17 23:29 UTCOSV refresh
  37. 2026-07-16 17:00 UTCEPSS rescore
  38. 2026-07-15 16:55 UTCEPSS rescore
  39. 2026-07-15 16:55 UTCEPSS rescore
  40. 2026-07-15 01:57 UTCEPSS rescore
  41. 2026-07-13 22:27 UTCEPSS rescore
  42. 2026-07-13 22:27 UTCEPSS rescore
  43. 2026-07-13 06:10 UTCEPSS rescore
  44. 2026-07-13 06:10 UTCEPSS rescore
  45. 2026-07-12 05:44 UTCEPSS rescore
  46. 2026-07-12 05:44 UTCEPSS rescore
  47. 2026-07-11 08:25 UTCEPSS rescore
  48. 2026-07-09 19:07 UTCEPSS rescore
  49. 2026-07-08 15:12 UTCEPSS rescore
  50. 2026-07-07 13:43 UTCEPSS rescore
  51. 2026-07-06 16:25 UTCEPSS rescore
  52. 2026-07-06 02:21 UTCEPSS rescore
  53. 2026-07-06 02:21 UTCEPSS rescore
  54. 2026-07-05 02:28 UTCEPSS rescore
  55. 2026-07-05 02:28 UTCEPSS rescore
  56. 2026-07-04 06:29 UTCEPSS rescore
  57. 2026-07-04 06:29 UTCEPSS rescore
  58. 2026-07-02 16:57 UTCEPSS rescore
  59. 2026-07-01 15:03 UTCEPSS rescore
  60. 2026-06-30 23:20 UTCEPSS rescore
  61. 2026-06-30 23:20 UTCEPSS rescore
  62. 2026-06-29 20:32 UTCOSV refresh
  63. 2026-06-29 14:04 UTCEPSS rescore
  64. 2026-06-29 14:04 UTCEPSS rescore
  65. 2026-06-28 14:05 UTCEPSS rescore
  66. 2026-06-28 04:54 UTCEPSS rescore
  67. 2026-06-28 04:54 UTCEPSS rescore
  68. 2026-06-27 03:06 UTCEPSS rescore
  69. 2026-06-27 03:06 UTCEPSS rescore
  70. 2026-06-25 13:48 UTCEPSS rescore
  71. 2026-06-25 13:48 UTCEPSS rescore
  72. 2026-06-24 14:03 UTCEPSS rescore
  73. 2026-06-24 14:03 UTCEPSS rescore
  74. 2026-06-23 21:31 UTCEPSS rescore
  75. 2026-06-23 21:31 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2021-20322?
CVE-2021-20322 is a high vulnerability published on February 18, 2022. A flaw in the processing of received ICMP errors (ICMP fragment needed and ICMP redirect) in the Linux kernel functionality was found to allow the ability to quickly scan open UDP ports. This flaw allows an off-path remote user to effectively bypass the source port UDP randomization. The highest…
When was CVE-2021-20322 disclosed?
CVE-2021-20322 was first published in the National Vulnerability Database on February 18, 2022, with the most recent update on July 30, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-20322 actively exploited?
CVE-2021-20322 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 7% probability of exploitation in the next 30 days, which ranks it in the top 6.4% of all scored CVEs.
What is the CVSS score of CVE-2021-20322?
CVE-2021-20322 has a CVSS v3 base score of 7.4 (NVD).
How do I remediate CVE-2021-20322?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-20322, 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.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-20322

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