CVE-2026-43037

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

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

Triggered by: GitHub Security Advisory CVSS
Sources: cna:linux, epss, ghsa
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.8Exploit: None knownExposed: 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)
EG Risk
49(Track)
EG Risk 49/100SSVC: 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
Severity98% × 45%
Exploitation1% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
46%
KEV
Not listed

Published

May 1, 2026

Last Modified

September 1, 2026

Advisory Details (10)

Auto-updated Sep 15, 2026
No patch confirmed yet.
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/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/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/1063515ce15ff31065c4e7f8265f4c2fd3c54876
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/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/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/ea9f65b27c8404e164848ebff1443310fd187629
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

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(25)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatrhcos-4.22.9.8.202607220526-02026-07-28redhat
redhatkernel-rt-0:3.10.0-1160.155.1.rt56.1307.el72026-07-17redhat
redhatrhcos-417.94.202606250942-02026-07-09redhat
redhatrhcos-415.92.202606200237-02026-07-06redhat
redhatrhcos-414.92.202606231112-02026-07-01redhat
redhatkernel-0:6.12.0-231.12.el10nv2026-06-30redhat
redhatrhcos-413.92.202606160406-02026-06-25redhat
redhatrhcos-412.86.202606140301-02026-06-25redhat
redhatkpatch-patch2026-06-24redhat
redhatkernel-0:2.6.32-754.61.1.el62026-06-22redhat
redhatkernel-0:3.10.0-1160.153.1.el72026-06-22redhat
redhatrhcos-416.94.202606051757-02026-06-18redhat
redhatrhcos-418.94.202606051320-02026-06-17redhat
redhatrhcos-4.19.9.6.202606100451-02026-06-17redhat
redhatkernel-0:4.18.0-305.194.1.el8_42026-06-17redhat
redhatrhcos-4.21.9.6.202606101139-02026-06-16redhat
redhatrhcos-4.20.9.6.202606101223-02026-06-16redhat
redhatkernel-0:4.18.0-372.195.1.el8_62026-06-12redhat
redhatkernel-0:6.12.0-212.10.el10nv2026-06-12redhat
redhatkernel-0:6.12.0-211.22.1.el10_22026-06-11redhat
redhatkernel-0:5.14.0-687.15.1.el9_82026-06-11redhat
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
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.

Affected Packages

(5 across 4 ecosystems)
Debian:11(2)
PackageVulnerable rangeFixed inDependents
linux5.10.103-1 ... 5.10.92-2 (53 versions)5.10.257-1—
linux-6.16.1.106-3~deb11u1 ... 6.1.164-1~deb11u1 (16 versions)6.1.170-1~deb11u1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
linux6.1.106-1 ... 6.1.99-1 (48 versions)6.1.170-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
linux6.12.38-1 ... 6.12.85-1~bpo12+1 (17 versions)6.12.85-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux6.12.100-1 ... 6.19~rc8-1~exp1 (125 versions)6.19.12-1—

Weakness Classification(2)

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

Additional Vendor Advisories

(15)

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 / 33× 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 420 total refreshes for this CVE.

  1. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-17 19:31 UTCEPSS rescore
  3. 2026-09-16 14:08 UTCEPSS rescore
  4. 2026-09-16 05:15 UTCEPSS rescore
  5. 2026-09-13 16:47 UTCEPSS rescore
  6. 2026-09-12 15:01 UTCEPSS rescore
  7. 2026-09-11 14:53 UTCEPSS rescore
  8. 2026-09-11 09:37 UTCEPSS rescore
  9. 2026-09-10 09:34 UTCEPSS rescore
  10. 2026-09-08 22:00 UTCEPSS rescore
  11. 2026-09-07 16:01 UTCEPSS rescore
  12. 2026-09-06 13:47 UTCEPSS rescore
  13. 2026-09-04 05:06 UTCEPSS rescore
  14. 2026-09-02 14:12 UTCEPSS rescore
  15. 2026-09-01 13:54 UTCEPSS rescore
  16. 2026-09-01 12:22 UTCEG score recompute
  17. 2026-09-01 12:22 UTCVendor advisory
  18. 2026-09-01 12:22 UTCGHSA enrichment
  19. 2026-08-30 19:17 UTCEPSS rescore
  20. 2026-08-30 01:22 UTCEPSS rescore
  21. 2026-08-28 21:41 UTCEPSS rescore
  22. 2026-08-27 14:25 UTCEPSS rescore
  23. 2026-08-26 14:46 UTCEPSS rescore
  24. 2026-08-25 13:49 UTCEPSS rescore
  25. 2026-08-24 12:27 UTCEG score recompute
Show 75 more
  1. 2026-08-24 12:27 UTCVendor advisory
  2. 2026-08-24 12:26 UTCGHSA enrichment
  3. 2026-08-23 21:51 UTCEG score recompute
  4. 2026-08-23 21:51 UTCVendor advisory
  5. 2026-08-23 21:50 UTCGHSA enrichment
  6. 2026-08-23 00:19 UTCEPSS rescore
  7. 2026-08-21 23:49 UTCEPSS rescore
  8. 2026-08-20 22:55 UTCEPSS rescore
  9. 2026-08-19 17:03 UTCEPSS rescore
  10. 2026-08-18 13:48 UTCEPSS rescore
  11. 2026-08-17 13:47 UTCEPSS rescore
  12. 2026-08-17 13:21 UTCEG score recompute
  13. 2026-08-17 13:21 UTCVendor advisory
  14. 2026-08-17 13:21 UTCGHSA enrichment
  15. 2026-08-16 14:56 UTCEPSS rescore
  16. 2026-08-16 09:15 UTCVendor advisory
  17. 2026-08-16 09:15 UTCGHSA enrichment
  18. 2026-08-16 05:16 UTCEG score recompute
  19. 2026-08-16 05:16 UTCVendor advisory
  20. 2026-08-16 05:16 UTCGHSA enrichment
  21. 2026-08-16 02:14 UTCEPSS rescore
  22. 2026-08-15 02:19 UTCEG score recompute
  23. 2026-08-15 02:19 UTCVendor advisory
  24. 2026-08-15 02:19 UTCGHSA enrichment
  25. 2026-08-15 01:30 UTCEPSS rescore
  26. 2026-08-14 22:32 UTCVendor advisory
  27. 2026-08-14 22:32 UTCGHSA enrichment
  28. 2026-08-14 18:46 UTCVendor advisory
  29. 2026-08-14 18:46 UTCGHSA enrichment
  30. 2026-08-14 15:01 UTCVendor advisory
  31. 2026-08-14 15:01 UTCGHSA enrichment
  32. 2026-08-14 11:15 UTCVendor advisory
  33. 2026-08-14 11:15 UTCGHSA enrichment
  34. 2026-08-14 07:29 UTCVendor advisory
  35. 2026-08-14 07:29 UTCGHSA enrichment
  36. 2026-08-14 03:44 UTCEG score recompute
  37. 2026-08-14 03:44 UTCVendor advisory
  38. 2026-08-14 03:44 UTCGHSA enrichment
  39. 2026-08-13 22:00 UTCEPSS rescore
  40. 2026-08-13 08:36 UTCVendor advisory
  41. 2026-08-13 08:36 UTCGHSA enrichment
  42. 2026-08-13 04:51 UTCVendor advisory
  43. 2026-08-13 04:51 UTCGHSA enrichment
  44. 2026-08-13 01:05 UTCVendor advisory
  45. 2026-08-13 01:05 UTCGHSA enrichment
  46. 2026-08-12 21:20 UTCVendor advisory
  47. 2026-08-12 21:20 UTCGHSA enrichment
  48. 2026-08-12 17:23 UTCEG score recompute
  49. 2026-08-12 17:23 UTCVendor advisory
  50. 2026-08-12 17:23 UTCGHSA enrichment
  51. 2026-08-12 13:51 UTCEPSS rescore
  52. 2026-08-12 12:38 UTCEG score recompute
  53. 2026-08-12 12:38 UTCVendor advisory
  54. 2026-08-12 12:38 UTCGHSA enrichment
  55. 2026-08-12 12:13 UTCVendor advisory
  56. 2026-08-12 12:13 UTCGHSA enrichment
  57. 2026-08-11 23:54 UTCVendor advisory
  58. 2026-08-11 23:54 UTCGHSA enrichment
  59. 2026-08-11 20:09 UTCVendor advisory
  60. 2026-08-11 20:09 UTCGHSA enrichment
  61. 2026-08-11 16:16 UTCEG score recompute
  62. 2026-08-11 16:16 UTCVendor advisory
  63. 2026-08-11 16:16 UTCGHSA enrichment
  64. 2026-08-11 13:43 UTCEPSS rescore
  65. 2026-08-11 09:19 UTCVendor advisory
  66. 2026-08-11 09:19 UTCGHSA enrichment
  67. 2026-08-11 05:33 UTCVendor advisory
  68. 2026-08-11 05:33 UTCGHSA enrichment
  69. 2026-08-11 01:47 UTCEG score recompute
  70. 2026-08-11 01:47 UTCVendor advisory
  71. 2026-08-11 01:47 UTCGHSA enrichment
  72. 2026-08-11 00:00 UTCEPSS rescore
  73. 2026-08-10 12:50 UTCVendor advisory
  74. 2026-08-10 12:50 UTCGHSA enrichment
  75. 2026-08-10 09:05 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 September 1, 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 1% probability of exploitation in the next 30 days, which ranks it in the top 54.4% of all scored CVEs.
What is the CVSS score of CVE-2026-43037?
CVE-2026-43037 has a CVSS v4.0 base score of 9.8 (CNA self-assessment; NVD's own analysis pending).
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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-43037

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