CVE-2026-43037

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-05-01. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 9.8Exploit: NoneExposed: 0

A fix is available — apply it.

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

ip6_tunnel: clear skb2->cb[] in ip4ip6_err()

Oskar Kjos reported the following problem.

ip4ip6_err() calls icmp_send() on a cloned skb whose cb[] was written by the IPv6 receive path as struct inet6_skb_parm. icmp_send() passes IPCB(skb2) to __ip_options_echo(), which interprets that cb[] region as struct inet_skb_parm (IPv4). The layouts differ: inet6_skb_parm.nhoff at offset 14 overlaps inet_skb_parm.opt.rr, producing a non-zero rr value. __ip_options_echo() then reads optlen from attacker-controlled packet data at sptr[rr+1] and copies that many bytes into dopt->__data, a fixed 40-byte stack buffer (IP_OPTIONS_DATA_FIXED_SIZE).

To fix this we clear skb2->cb[], as suggested by Oskar Kjos.

Also add minimal IPv4 header validation (version == 4, ihl >= 5).

CVSS v3
9.8
EG Score
9.8(medium)
EPSS
43.4%
KEV
Not listed

Published

May 1, 2026

Last Modified

July 20, 2026

Advisory Details (10)

Auto-updated Jul 20, 2026
Patch available. Sources: redhat.
redhat Patch Available

Affected: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions.

https://access.redhat.com/errata/RHSA-2026:22940
redhat Patch Available

Affected: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions.

https://access.redhat.com/errata/RHSA-2026:22900
generic

ip6_tunnel: clear skb2->cb[] in ip4ip6_err() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/ea9f65b27c8404e164848ebff1443310fd187629
generic

ip6_tunnel: clear skb2->cb[] in ip4ip6_err() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/d6621f60192fe10c047a4487be42a6f4c150707f
generic

ip6_tunnel: clear skb2->cb[] in ip4ip6_err() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/a0c4ce9900a108eaf55d0f3b399cb55999647d39
generic

ip6_tunnel: clear skb2->cb[] in ip4ip6_err() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/590f622669b97eaf7b57a1de7b0a6e68c5d8b2c3
generic

ip6_tunnel: clear skb2->cb[] in ip4ip6_err() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/4a622658f384b03560834cbe8ffcfe69a278f7c8
generic

ip6_tunnel: clear skb2->cb[] in ip4ip6_err() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/2edfa31769a4add828a7e604b21cb82aaaa05925
generic

ip6_tunnel: clear skb2->cb[] in ip4ip6_err() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/2cc6e3b0fe0f0242d1f530a93a4924f48ab85ba5
generic

ip6_tunnel: clear skb2->cb[] in ip4ip6_err() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/1063515ce15ff31065c4e7f8265f4c2fd3c54876

Vendor Advisories for CVE-2026-43037(20)

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

Patch Availability(13)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatkernel-0:6.12.0-212.10.el10nv2026-06-12redhat
redhatkernel-0:4.18.0-372.195.1.el8_62026-06-12redhat
redhatkernel-0:5.14.0-687.15.1.el9_82026-06-11redhat
redhatkernel-0:6.12.0-211.22.1.el10_22026-06-11redhat
redhatkernel-rt-0:4.18.0-553.132.1.rt7.473.el8_102026-06-10redhat
redhatkernel-0:4.18.0-553.132.1.el8_102026-06-10redhat
redhatkernel-0:6.12.0-55.77.1.el10_02026-06-08redhat
redhatkernel-0:4.18.0-477.145.1.el8_82026-06-04redhat
redhatkernel-0:5.14.0-427.129.1.el9_42026-06-04redhat
redhatkernel-0:5.14.0-570.119.1.el9_62026-06-04redhat
redhatkernel-0:5.14.0-284.174.1.el9_22026-06-03redhat
redhatkernel-rt-0:5.14.0-284.174.1.rt14.459.el9_22026-06-03redhat
linuxKernel @ 5.10.253—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.

Weakness Classification(2)

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

All Vendor Advisories

(12)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 8× in last 7d / 31× 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 222 total refreshes for this CVE.

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

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-43037?
CVE-2026-43037 is a critical vulnerability published on May 1, 2026. In the Linux kernel, the following vulnerability has been resolved: ip6tunnel: clear skb2->cb[] in ip4ip6err() Oskar Kjos reported the following problem. ip4ip6err() calls icmpsend() on a cloned skb whose cb[] was written by the IPv6 receive path as struct inet6skbparm. icmp_send() passes…
When was CVE-2026-43037 disclosed?
CVE-2026-43037 was first published in the National Vulnerability Database on May 1, 2026, with the most recent update on July 20, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-43037 actively exploited?
CVE-2026-43037 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 43.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-43037?
CVE-2026-43037 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-43037?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-43037, 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

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