Vigie VulnDBEuropean-hosted Vulnerability DB
FR
Menu

ip6_tunnel: clear skb2->cb[] in ip4ip6_err() (Linux Linux)

CVE-2026-43037
CRITICAL 9.8

At a glance

Source
NVD
EPSS
EPSS 0.69 % · percentile 53 ()
State
PUBLISHED
Published
Updated
Assigner
Linux
NVD status
Modified

Search on…

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).

Weaknesses (CWE)

  • CWE-843 — Access of Resource Using Incompatible Type
  • CWE-121 — Stack-based Buffer Overflow
  • CWE-787 — Out-of-bounds Write

References

Scores

VersionScoreVectorScored by
CVSS 3.1CRITICAL 9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HLinux
CVSS 3.1HIGH 8.8CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hredhat-SADP
CVSS 3.1CRITICAL 9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HNVD · 416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Secondary)
CVSS 3.1HIGH 8.8CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HNVD · 0b0ca135-0b70-47e7-9f44-1890c2a1c46c (Secondary)

European references

CERT-FR advisories

Affected configurations (NVD CPE)

Affected products

ProductVersions
Linux · Linuxaffected c4d3efafcc933fd2ffd169d7dc4f980393a13796 < ea9f65b27c8404e164848ebff1443310fd187629 ; affected c4d3efafcc933fd2ffd169d7dc4f980393a13796 < d6621f60192fe10c047a4487be42a6f4c150707f ; affected c4d3efafcc933fd2ffd169d7dc4f980393a13796 < 2cc6e3b0fe0f0242d1f530a93a4924f48ab85ba5 ; affected c4d3efafcc933fd2ffd169d7dc4f980393a13796 < a0c4ce9900a108eaf55d0f3b399cb55999647d39 ; affected c4d3efafcc933fd2ffd169d7dc4f980393a13796 < 1063515ce15ff31065c4e7f8265f4c2fd3c54876 ; affected c4d3efafcc933fd2ffd169d7dc4f980393a13796 < 590f622669b97eaf7b57a1de7b0a6e68c5d8b2c3
Linux · Linuxaffected 2.6.22 ; unaffected 0 < 2.6.22 ; unaffected 5.10.253 ≤ 5.10.* ; unaffected 5.15.203 ≤ 5.15.* ; unaffected 6.1.168 ≤ 6.1.* ; unaffected 6.6.134 ≤ 6.6.*

Sources

SourceLicence
CVE List (CVEProject cvelistV5)CVE Program Terms of Use
EPSS (FIRST.org)FIRST — attribution requested
ENISA EUVDENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feedsPublic domain — this product uses data from the NVD API but is not endorsed or certified by the NVD