CVE-2026-43037

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

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

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
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
44%
KEV
Not listed

Published

May 1, 2026

Last Modified

August 12, 2026

Advisory Details (10)

Auto-updated Aug 19, 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(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-4.19.9.6.202606100451-02026-06-17redhat
redhatkernel-0:4.18.0-305.194.1.el8_42026-06-17redhat
redhatrhcos-418.94.202606051320-02026-06-17redhat
redhatrhcos-4.20.9.6.202606101223-02026-06-16redhat
redhatrhcos-4.21.9.6.202606101139-02026-06-16redhat
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-0:4.18.0-553.132.1.el8_102026-06-10redhat
redhatkernel-rt-0:4.18.0-553.132.1.rt7.473.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 (122 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 26× in last 7d / 167× 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 388 total refreshes for this CVE.

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

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 August 12, 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 55.6% of all scored CVEs.
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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