CVE-2026-43037ip6_tunnel: clear skb2->cb[] in ip4ip6_err()
Updated under an hour ago ()
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It affects Linux and 12 other products. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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
- 9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- CWE-843
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Oct 16, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from c4d3efafcc933fd2ffd169d7dc4f980393a13796 before ea9f65b27c8404e164848ebff1443310fd187629; from c4d3efafcc933fd2ffd169d7dc4f980393a13796 before d6621f60192fe10c047a4487be42a6f4c150707f; from c4d3efafcc933fd2ffd169d7dc4f980393a13796 before 2cc6e3b0fe0f0242d1f530a93a4924f48ab85ba5; from c4d3efafcc933fd2ffd169d7dc4f980393a13796 before a0c4ce9900a108eaf55d0f3b399cb55999647d39; from c4d3efafcc933fd2ffd169d7dc4f980393a13796 before 1063515ce15ff31065c4e7f8265f4c2fd3c54876; from c4d3efafcc933fd2ffd169d7dc4f980393a13796 before 590f622669b97eaf7b57a1de7b0a6e68c5d8b2c3; from c4d3efafcc933fd2ffd169d7dc4f980393a13796 before 4a622658f384b03560834cbe8ffcfe69a278f7c8; from c4d3efafcc933fd2ffd169d7dc4f980393a13796 before 2edfa31769a4add828a7e604b21cb82aaaa05925 | CNA record |
Red Hat NVIDIA for RHEL 10 redhat:enterprise_linux_nvidia | from 0:6.12.0-212.10.el10nv not affected; from 0:6.12.0-231.12.el10nv not affected | CISA ADP |
Red Hat Red Hat Enterprise Linux 10 redhat:enterprise_linux | from 0:6.12.0-211.22.1.el10_2 not affected | CISA ADP |
Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support redhat:enterprise_linux_eus | from 0:6.12.0-55.77.1.el10_0 not affected | CISA ADP |
from 0:2.6.32-754.61.1.el6 not affected | CISA ADP | |
Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support redhat:rhel_extras_rt_els | from 0:3.10.0-1160.155.1.rt56.1307.el7 not affected | CISA ADP |
from 0:4.18.0-305.194.1.el8_4 not affected | CISA ADP | |
Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On redhat:rhel_eus_long_life | from 0:4.18.0-305.194.1.el8_4 not affected | CISA ADP |
from 0:4.18.0-477.145.1.el8_8 not affected | CISA ADP | |
from 0:4.18.0-477.145.1.el8_8 not affected | CISA ADP | |
Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support redhat:rhel_eus | from 0:5.14.0-570.119.1.el9_6 not affected | CISA ADP |
Red Hat Red Hat OpenShift Container Platform 4.12 redhat:openshift | from 412.86.202606140301-0 not affected | CISA ADP |
linux linux_kernel linux:linux_kernel | from 2.6.22 before 5.10.253; from 5.11 before 5.15.203; from 5.16 before 6.1.168; from 6.2 before 6.6.134; from 6.7 before 6.12.81; from 6.13 before 6.18.22; from 6.19 before 6.19.12; 7.0; and 5 more ranges | NVD |
References
- https://git.kernel.org/stable/c/ea9f65b27c8404e164848ebff1443310fd187629patch
- https://git.kernel.org/stable/c/d6621f60192fe10c047a4487be42a6f4c150707fpatch
- https://git.kernel.org/stable/c/2cc6e3b0fe0f0242d1f530a93a4924f48ab85ba5patch
- https://git.kernel.org/stable/c/a0c4ce9900a108eaf55d0f3b399cb55999647d39patch
- https://git.kernel.org/stable/c/1063515ce15ff31065c4e7f8265f4c2fd3c54876patch
- https://git.kernel.org/stable/c/590f622669b97eaf7b57a1de7b0a6e68c5d8b2c3patch
- https://git.kernel.org/stable/c/4a622658f384b03560834cbe8ffcfe69a278f7c8patch
- https://git.kernel.org/stable/c/2edfa31769a4add828a7e604b21cb82aaaa05925patch
- https://access.redhat.com/errata/RHSA-2026:22900
- https://access.redhat.com/errata/RHSA-2026:22940
- https://access.redhat.com/errata/RHSA-2026:22964
- https://access.redhat.com/errata/RHSA-2026:23224
- https://access.redhat.com/errata/RHSA-2026:23237
- https://access.redhat.com/errata/RHSA-2026:24343
- https://access.redhat.com/errata/RHSA-2026:25044
- https://access.redhat.com/errata/RHSA-2026:25120
- https://access.redhat.com/errata/RHSA-2026:25121
- https://access.redhat.com/errata/RHSA-2026:25181
- https://access.redhat.com/errata/RHSA-2026:25186
- https://access.redhat.com/errata/RHSA-2026:25191
- https://access.redhat.com/errata/RHSA-2026:25193
- https://access.redhat.com/errata/RHSA-2026:25200
- https://access.redhat.com/errata/RHSA-2026:25217
- https://access.redhat.com/errata/RHSA-2026:25533
- https://access.redhat.com/errata/RHSA-2026:25534
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.