CVE-2026-63994

CRITICALPre-NVD 9.89.8
EchelonGraph scoreMEDIUM confidence

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

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-07-19. A secondary CVSS source baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — Patch released this week
9.8EG
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: 0.5%CVSS: 9.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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

tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()

Sashiko found that iptunnel_pmtud_build_icmp() and iptunnel_pmtud_build_icmpv6() were caching ip_hdr() and ipv6_hdr() before an skb_cow() call which can reallocate skb->head.

Fix this possible UAF by initializing the local variables after the skb_cow() call.

Remove skb_reset_network_header() calls which were not needed.

CVSS v3
9.8
EG Score
9.8CRITICALmedium confidence
EG Risk
44
EG Risk 44/100

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 (value × EchelonGraph’s weight)
Severity98% × 45%
The EG Score, 9.8 of 10.
Exploitation0.5% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's BOD 26-04 default: no one has published Automatable for this CVE, and CISA treats it as “no” for a CVE not in KEV.
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from 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
0.5%
EPSS %ILE
42nd
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

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

Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from 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)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

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

July 19, 2026

Last Modified

October 7, 2026

Advisory Details (8)

Auto-updated Oct 7, 2026
Patch available.
Web page

tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/f3f204541f280a6ecb04503a0d6794d93990ca43
Web page

tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/bf8b3f34c37c162357138e7c0942723b8b94fed1
Web page

tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/b4bc94353050b1fa7b702bd4c6600710dd926cff
Web page

tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/95b6d772bfe788331d9742d73eaa12e113b2adc4
Web page

tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/76cd9398a0470257ab765bdf5f358a2af2e17934
Web page

tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/7254aef4d1a7e18e887af9010e2f2dc34806789b
Web page

tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/6dff77899b9e9fe5d854abda3a98ad04e7229ef7
Web page

tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/50750d86a2e5266aba0c295483b3397843198b11

Patch Availability(27)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulinux-xilinx-zynqmp-tools-5.15.0-1079 (5.15.0-1079.83) @ jammy2026-10-13ubuntu
ubuntulinux-tools-oracle-edge (7.0.0-1011.11~24.04.1) @ noble2026-10-13ubuntu
ubuntulinux-tools-nvidia-lowlatency-64k-6.8 (6.8.0-1063.66.1) @ noble2026-10-13ubuntu
ubuntulinux-tools-intel-iotg-edge (5.15.0.1111.117~20.04.1) @ focal2026-10-13ubuntu
ubuntulinux-tools-azure-fde-7.0 (7.0.0-1009.9) @ resolute2026-10-13ubuntu
ubuntulinux-tools-nvidia-hwe-26.04 (7.0.0-2016.16) @ resolute2026-10-13ubuntu
ubuntulinux-tools-gcp-edge (7.0.0-1011.11~24.04.1) @ noble2026-10-13ubuntu
ubuntulinux-virtual-hwe-20.04-edge (5.15.0.194.171) @ jammy2026-10-13ubuntu
ubuntulinux-tools-aws-lts-24.04 (6.8.0-1065.68) @ noble2026-10-13ubuntu
ubuntulinux-tools-nvidia-tegra-rt-5.15 (5.15.0.1068.68) @ jammy2026-10-13ubuntu
ubuntulinux-tools-ibm-edge (6.8.0-1066.67~22.04.1) @ jammy2026-10-13ubuntu
ubuntulinux-tools-raspi-realtime-7.0 (7.0.0-1015.15) @ resolute2026-10-13ubuntu
ubuntulinux-tools-nvidia-hwe-24.04-edge (7.0.0-1016.16) @ resolute2026-10-13ubuntu
ubuntulinux-tools-azure-edge (7.0.0-1014.14~24.04.1) @ noble2026-10-13ubuntu
ubuntulinux-tools-ibm-edge (5.15.0.1110.114~20.04.1) @ focal2026-10-13ubuntu
ubuntulinux-tools-aws-fips-6.8 (6.8.0-1065.68+fips1) @ noble2026-10-13ubuntu
ubuntulinux-tools-nvidia-tegra-rt-5.15 (5.15.0.1068.70~20.04.1) @ focal2026-10-13ubuntu
ubuntulinux-tools-fips-5.15 (5.15.0.194.113) @ jammy2026-10-13ubuntu
ubuntulinux-tools-raspi-nolpae (5.15.0.1110.108) @ jammy2026-10-13ubuntu
ubuntulinux-tools-gcp-edge (5.15.0.1118.128~20.04.1) @ focal2026-10-13ubuntu
ubuntulinux-tools-oracle-7.0 (7.0.0-1008.8) @ resolute2026-10-13ubuntu
ubuntulinux-tools-oracle-edge (5.15.0.1114.120~20.04.1) @ focal2026-10-13ubuntu
ubuntulinux-tools-nvidia-tegra-rt-6.8 (6.8.0-1035.38) @ noble2026-10-13ubuntu
ubuntulinux-tools-realtime-hwe-22.04 (6.8.1-1060.61~22.04.1) @ jammy2026-10-13ubuntu
redhatkernel-0:5.14.0-687.55.1.el9_82026-10-08redhat
redhatkernel-0:4.18.0-553.171.1.el8_102026-10-05redhat
redhatkernel-rt-0:4.18.0-553.171.1.rt7.512.el8_102026-10-05redhat

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 (54 versions)
  • every version up to 5.10.259-1: fixed in 5.10.259-1
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.1.106-1 ... 6.1.99-1 (53 versions)
  • every version up to 6.1.176-1: fixed in 6.1.176-1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.38-1 ... 6.12.94-1~bpo12+1 (27 versions)
  • every version up to 6.12.94-1: fixed in 6.12.94-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 7.0.9-1~bpo13+1 (142 versions)
  • every version up to 7.0.12-1: fixed in 7.0.12-1
—

Weakness Classification(1)

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

Additional Vendor Advisories

(22)

Data Freshness Timeline

(refreshed 22× in last 7d / 73× 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 100 of 590 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. None are among the latest 100 rows. The 490 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-14 09:03 UTCEG score recompute
  2. 2026-10-14 09:03 UTCVendor advisory
  3. 2026-10-14 09:02 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  4. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  5. 2026-10-13 05:47 UTCEG score recompute
  6. 2026-10-13 05:47 UTCVendor advisory
  7. 2026-10-13 05:47 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  8. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  9. 2026-10-12 15:48 UTCEG score recompute
  10. 2026-10-12 06:12 UTCVendor advisory
  11. 2026-10-12 06:12 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  12. 2026-10-11 19:33 UTCEG score recompute
  13. 2026-10-11 16:48 UTCEG score recompute
  14. 2026-10-11 14:09 UTCEG score recompute
  15. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  16. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  17. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  18. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  19. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  20. 2026-10-07 20:42 UTCEG score recompute
  21. 2026-10-07 20:42 UTCVendor advisory
  22. 2026-10-07 20:41 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  23. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  24. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  25. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 41st percentile
Show 75 more
  1. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  2. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  3. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  4. 2026-10-01 12:45 UTCVendor advisory
  5. 2026-10-01 12:44 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  6. 2026-10-01 08:47 UTCEG score recompute
  7. 2026-10-01 08:47 UTCVendor advisory
  8. 2026-10-01 08:47 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  9. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  10. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  11. 2026-09-28 13:11 UTCVendor advisory
  12. 2026-09-28 13:11 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  13. 2026-09-28 07:25 UTCEG score recompute
  14. 2026-09-28 07:25 UTCVendor advisory
  15. 2026-09-28 07:25 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  16. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  17. 2026-09-24 13:13 UTCVendor advisory
  18. 2026-09-24 13:13 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  19. 2026-09-24 08:27 UTCVendor advisory
  20. 2026-09-24 08:26 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  21. 2026-09-24 03:39 UTCEG score recompute
  22. 2026-09-24 03:39 UTCVendor advisory
  23. 2026-09-24 03:39 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  24. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  25. 2026-09-23 09:58 UTCVendor advisory
  26. 2026-09-23 09:58 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  27. 2026-09-23 06:01 UTCVendor advisory
  28. 2026-09-23 06:01 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  29. 2026-09-23 02:04 UTCEG score recompute
  30. 2026-09-23 02:04 UTCVendor advisory
  31. 2026-09-23 02:04 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  32. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  33. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  34. 2026-09-18 09:15 UTCVendor advisory
  35. 2026-09-18 09:15 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  36. 2026-09-18 04:21 UTCEG score recompute
  37. 2026-09-18 04:21 UTCVendor advisory
  38. 2026-09-18 04:21 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  39. 2026-09-17 09:58 UTCVendor advisory
  40. 2026-09-17 09:58 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  41. 2026-09-17 05:34 UTCEG score recompute
  42. 2026-09-17 05:34 UTCVendor advisory
  43. 2026-09-17 05:34 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  44. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  45. 2026-09-16 13:00 UTCEG score recompute
  46. 2026-09-16 13:00 UTCVendor advisory
  47. 2026-09-16 13:00 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  48. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  49. 2026-09-14 10:54 UTCVendor advisory
  50. 2026-09-14 10:54 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  51. 2026-09-14 06:57 UTCVendor advisory
  52. 2026-09-14 06:57 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  53. 2026-09-14 02:59 UTCVendor advisory
  54. 2026-09-14 02:59 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  55. 2026-09-13 22:58 UTCEG score recompute
  56. 2026-09-13 22:58 UTCVendor advisory
  57. 2026-09-13 22:58 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  58. 2026-09-13 16:12 UTCVendor advisory
  59. 2026-09-13 16:12 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  60. 2026-09-13 11:45 UTCVendor advisory
  61. 2026-09-13 11:45 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  62. 2026-09-13 07:26 UTCVendor advisory
  63. 2026-09-13 07:26 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  64. 2026-09-13 03:28 UTCVendor advisory
  65. 2026-09-13 03:28 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  66. 2026-09-12 21:23 UTCVendor advisory
  67. 2026-09-12 21:23 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  68. 2026-09-12 16:38 UTCEG score recompute
  69. 2026-09-12 16:38 UTCVendor advisory
  70. 2026-09-12 16:38 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  71. 2026-09-12 12:34 UTCVendor advisory
  72. 2026-09-12 12:34 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  73. 2026-09-12 07:16 UTCVendor advisory
  74. 2026-09-12 07:16 UTCGHSA enrichmentGHSA-hvgq-ch9f-27rq · GitHub severity CRITICAL · GitHub CVSS 9.8
  75. 2026-09-12 01:09 UTCVendor advisory

Frequently asked(5)

What is CVE-2026-63994?
CVE-2026-63994 is a critical-severity vulnerability; its CVE record was published on July 19, 2026. In the Linux kernel, the following vulnerability has been resolved: tunnels: load network headers after skbcow() in iptunnelpmtudbuildicmpv6 Sashiko found that iptunnelpmtudbuild_icmp() and iptunnelpmtudbuildicmpv6() were caching iphdr() and ipv6_hdr() before an skb_cow() call which can reallocate…
When was the CVE record for CVE-2026-63994 published?
The CVE record for CVE-2026-63994 was published on July 19, 2026. 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 October 7, 2026; the record at its source may have been updated since.
Is CVE-2026-63994 actively exploited?
CVE-2026-63994 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (42nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-63994?
CVE-2026-63994 has a CVSS base score of 9.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-63994?
A fix for CVE-2026-63994 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-63994 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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