CVE-2026-43037

Aliases:RHSA-2026:25534RHSA-2026:28738RHSA-2026:28740RHSA-2026:28741RHSA-2026:28742RHSA-2026:28748RHSA-2026:28749RHSA-2026:28750UBUNTU-CVE-2026-43037DEBIAN-CVE-2026-43037
Advisory lineage Upstream: 0 Downstream: 185
Modified
Published: 01 May 2026, 14:15
Last modified:01 Sept 2026, 12:04

Vulnerability Summary

Overall Risk (default)
high
70/100
CVSS Score
9.8 CRITICAL
v3.1 (cve.org)
EPSS Score
0.56% LOW
1% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

01 May 2026, 14:15
Published
Vulnerability first disclosed
01 Sept 2026, 12:04
Last Modified
Vulnerability information updated

Description

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 Metrics

  • v4.0•CRITICAL•Score: 9.2CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
  • v3.1•CRITICAL•Score: 9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
  • v3.1•HIGH•Score: 8.8CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Trends

Current EPSS score: 0.56%• Percentile: 46%

Techniques & Countermeasures

  • CWE-787•Out-of-bounds Write

    The product writes data past the end, or before the beginning, of the intended buffer.

  • CWE-843•Access of Resource Using Incompatible Type ('Type Confusion')

    The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.

Affected Systems

  • debian•linux

    < 5.10.257-1 | < 6.1.170-1 | < 6.12.85-1 | < 6.19.12-1

  • debian•linux-6.1

    < 6.1.170-1~deb11u1

  • ubuntu•linux

    all | < 3.13.0-214.265 | < 4.4.0-283.317 | < 4.15.0-253.265 | < 5.4.0-233.253 | < 5.15.0-185.195 | < 6.8.0-134.134 | < 6.17.0-40.40

  • ubuntu•linux-allwinner-5.19

    all

  • ubuntu•linux-aws

    all | < 4.4.0-1156.162 | < 4.4.0-1194.209 | < 4.15.0-1194.207 | < 5.4.0-1161.172 | < 5.15.0-1111.118 | < 6.8.0-1060.63 | < 6.17.0-1019.19

  • ubuntu•linux-aws-5.0

    all

  • ubuntu•linux-aws-5.11

    all

  • ubuntu•linux-aws-5.13

    all

  • ubuntu•linux-aws-5.15

    < 5.15.0-1111.118~20.04.1

  • ubuntu•linux-aws-5.19

    all

  • ubuntu•linux-aws-5.3

    all

  • ubuntu•linux-aws-5.4

    < 5.4.0-1161.172~18.04.1

  • ubuntu•linux-aws-5.8

    all

  • ubuntu•linux-aws-6.14

    all

  • ubuntu•linux-aws-6.17

    < 6.17.0-1019.19~24.04.1

  • ubuntu•linux-aws-6.2

    all

  • ubuntu•linux-aws-6.5

    all

  • ubuntu•linux-aws-6.8

    < 6.8.0-1060.63~22.04.1

  • ubuntu•linux-aws-fips

    < 4.15.0-2132.138 | all | < 5.4.0-1161.172+fips1 | < 5.15.0-1111.118+fips1 | < 6.8.0-1060.63+fips1

  • ubuntu•linux-aws-hwe

    all | < 4.15.0-1194.207~16.04.1

  • ubuntu•linux-azure

    all | < 4.15.0-1205.220~14.04.1 | < 4.15.0-1204.219~16.04.1 | all | < 5.4.0-1166.172 | < 5.15.0-1116.125 | < 6.8.0-1063.71 | all

  • ubuntu•linux-azure-4.15

    < 4.15.0-1204.219

  • ubuntu•linux-azure-5.11

    all

  • ubuntu•linux-azure-5.13

    all

  • ubuntu•linux-azure-5.15

    < 5.15.0-1116.125~20.04.1

  • ubuntu•linux-azure-5.19

    all

  • ubuntu•linux-azure-5.3

    all

  • ubuntu•linux-azure-5.4

    < 5.4.0-1166.172~18.04.1

  • ubuntu•linux-azure-5.8

    all

  • ubuntu•linux-azure-6.11

    all

  • ubuntu•linux-azure-6.14

    all

  • ubuntu•linux-azure-6.17

    < 6.17.0-1021.21~24.04.1

  • ubuntu•linux-azure-6.2

    all

  • ubuntu•linux-azure-6.5

    all

  • ubuntu•linux-azure-6.8

    < 6.8.0-1063.71~22.04.1

  • ubuntu•linux-azure-edge

    all

  • ubuntu•linux-azure-fde

    all | all | < 6.8.0-1062.69 | all | all

  • ubuntu•linux-azure-fde-5.15

    < 5.15.0-1116.125~20.04.1

  • ubuntu•linux-azure-fde-5.19

    all

  • ubuntu•linux-azure-fde-6.14

    all

  • ubuntu•linux-azure-fde-6.2

    all

  • ubuntu•linux-azure-fde-6.8

    < 6.8.0-1062.69~22.04.1

  • ubuntu•linux-azure-fde-7.0

    all

  • ubuntu•linux-azure-fips

    < 4.15.0-2112.118 | all | < 5.4.0-1166.172+fips1 | < 5.15.0-1116.125+fips1 | < 6.8.0-1062.69+fips1

  • ubuntu•linux-azure-nvidia

    all

  • ubuntu•linux-azure-nvidia-6.14

    all

  • ubuntu•linux-bluefield

    all | < 5.4.0-1120.127 | < 5.15.0-1095.97 | < 6.8.0-1026.30

  • ubuntu•linux-fips

    < 4.4.0-1126.133 | all | < 4.15.0-1149.161 | < 5.4.0-1135.145 | < 5.15.0-185.195+fips1 | < 6.8.0-134.134+fips1

  • ubuntu•linux-gcp

    all | < 4.15.0-1187.204~16.04.1 | all | < 5.4.0-1164.173 | < 5.15.0-1111.121 | < 6.8.0-1063.69 | < 6.17.0-1020.22

  • ubuntu•linux-gcp-4.15

    < 4.15.0-1187.204

Showing first 50 affected entries in server-rendered view.

References (100)