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
42.7%
KEV
Not listed

Published

May 1, 2026

Last Modified

July 2, 2026

Advisory Details (10)

Auto-updated Jul 3, 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(12)

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

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.

Additional Vendor Advisories

(11)

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 6× in last 7d / 147× 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 288 total refreshes for this CVE.

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

Related CVEs(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 2, 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 42.7% 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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