CVE-2026-43038 - Vulnerability Details

Vendors	Products
Linux	Linux Kernel

Link	Providers
https://git.kernel.org/stable/c/0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7
https://git.kernel.org/stable/c/1ceeebd5bd6d855b17a5df625109bfe29129d7cf
https://git.kernel.org/stable/c/3d5127d998de617b130aae96b138dba22ac6a8a7
https://git.kernel.org/stable/c/86ab3e55673a7a49a841838776f1ab18d23a67b5
https://git.kernel.org/stable/c/a2edbb6393972a02114b6003953a5cef3104fada
https://git.kernel.org/stable/c/a4437faf135da293d16fcc4cc607316742bd0ebb
https://git.kernel.org/stable/c/c438ba010171b70bad22fc18b1d5bdc3627476e8
https://git.kernel.org/stable/c/e41953e7d118e2702bcb217879c173d9d1d3cd4e

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach() Sashiko AI-review observed: In ip6_err_gen_icmpv6_unreach(), the skb is an outer IPv4 ICMP error packet where its cb contains an IPv4 inet_skb_parm. When skb is cloned into skb2 and passed to icmp6_send(), it uses IP6CB(skb2). IP6CB interprets the IPv4 inet_skb_parm as an inet6_skb_parm. The cipso offset in inet_skb_parm.opt directly overlaps with dsthao in inet6_skb_parm at offset 18. If an attacker sends a forged ICMPv4 error with a CIPSO IP option, dsthao would be a non-zero offset. Inside icmp6_send(), mip6_addr_swap() is called and uses ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO). This would scan the inner, attacker-controlled IPv6 packet starting at that offset, potentially returning a fake TLV without checking if the remaining packet length can hold the full 18-byte struct ipv6_destopt_hao. Could mip6_addr_swap() then perform a 16-byte swap that extends past the end of the packet data into skb_shared_info? Should the cb array also be cleared in ip6_err_gen_icmpv6_unreach() and ip6ip6_err() to prevent this? This patch implements the first suggestion. I am not sure if ip6ip6_err() needs to be changed. A separate patch would be better anyway.
Title		ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7 https://git.kernel.org/stable/c/1ceeebd5bd6d855b17a5df625109bfe29129d7cf https://git.kernel.org/stable/c/3d5127d998de617b130aae96b138dba22ac6a8a7 https://git.kernel.org/stable/c/86ab3e55673a7a49a841838776f1ab18d23a67b5 https://git.kernel.org/stable/c/a2edbb6393972a02114b6003953a5cef3104fada https://git.kernel.org/stable/c/a4437faf135da293d16fcc4cc607316742bd0ebb https://git.kernel.org/stable/c/c438ba010171b70bad22fc18b1d5bdc3627476e8 https://git.kernel.org/stable/c/e41953e7d118e2702bcb217879c173d9d1d3cd4e

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-43038", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-05-01T14:12:55.978Z", "datePublished": "2026-05-01T14:15:35.986Z", "dateUpdated": "2026-05-01T14:15:35.986Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-05-01T14:15:35.986Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()\n\nSashiko AI-review observed:\n\n In ip6_err_gen_icmpv6_unreach(), the skb is an outer IPv4 ICMP error packet\n where its cb contains an IPv4 inet_skb_parm. When skb is cloned into skb2\n and passed to icmp6_send(), it uses IP6CB(skb2).\n\n IP6CB interprets the IPv4 inet_skb_parm as an inet6_skb_parm. The cipso\n offset in inet_skb_parm.opt directly overlaps with dsthao in inet6_skb_parm\n at offset 18.\n\n If an attacker sends a forged ICMPv4 error with a CIPSO IP option, dsthao\n would be a non-zero offset. Inside icmp6_send(), mip6_addr_swap() is called\n and uses ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO).\n\n This would scan the inner, attacker-controlled IPv6 packet starting at that\n offset, potentially returning a fake TLV without checking if the remaining\n packet length can hold the full 18-byte struct ipv6_destopt_hao.\n\n Could mip6_addr_swap() then perform a 16-byte swap that extends past the end\n of the packet data into skb_shared_info?\n\n Should the cb array also be cleared in ip6_err_gen_icmpv6_unreach() and\n ip6ip6_err() to prevent this?\n\nThis patch implements the first suggestion.\n\nI am not sure if ip6ip6_err() needs to be changed.\nA separate patch would be better anyway."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/ipv6/icmp.c"], "versions": [{"version": "ca15a078bd907df5fc1c009477869c5cbde3b753", "lessThan": "c438ba010171b70bad22fc18b1d5bdc3627476e8", "status": "affected", "versionType": "git"}, {"version": "ca15a078bd907df5fc1c009477869c5cbde3b753", "lessThan": "0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7", "status": "affected", "versionType": "git"}, {"version": "ca15a078bd907df5fc1c009477869c5cbde3b753", "lessThan": "a4437faf135da293d16fcc4cc607316742bd0ebb", "status": "affected", "versionType": "git"}, {"version": "ca15a078bd907df5fc1c009477869c5cbde3b753", "lessThan": "3d5127d998de617b130aae96b138dba22ac6a8a7", "status": "affected", "versionType": "git"}, {"version": "ca15a078bd907df5fc1c009477869c5cbde3b753", "lessThan": "e41953e7d118e2702bcb217879c173d9d1d3cd4e", "status": "affected", "versionType": "git"}, {"version": "ca15a078bd907df5fc1c009477869c5cbde3b753", "lessThan": "a2edbb6393972a02114b6003953a5cef3104fada", "status": "affected", "versionType": "git"}, {"version": "ca15a078bd907df5fc1c009477869c5cbde3b753", "lessThan": "1ceeebd5bd6d855b17a5df625109bfe29129d7cf", "status": "affected", "versionType": "git"}, {"version": "ca15a078bd907df5fc1c009477869c5cbde3b753", "lessThan": "86ab3e55673a7a49a841838776f1ab18d23a67b5", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/ipv6/icmp.c"], "versions": [{"version": "3.13", "status": "affected"}, {"version": "0", "lessThan": "3.13", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.253", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.203", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.168", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.134", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.81", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.22", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.19.12", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.0", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "5.10.253"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "5.15.203"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "6.1.168"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "6.6.134"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "6.12.81"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "6.18.22"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "6.19.12"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "7.0"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/c438ba010171b70bad22fc18b1d5bdc3627476e8"}, {"url": "https://git.kernel.org/stable/c/0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7"}, {"url": "https://git.kernel.org/stable/c/a4437faf135da293d16fcc4cc607316742bd0ebb"}, {"url": "https://git.kernel.org/stable/c/3d5127d998de617b130aae96b138dba22ac6a8a7"}, {"url": "https://git.kernel.org/stable/c/e41953e7d118e2702bcb217879c173d9d1d3cd4e"}, {"url": "https://git.kernel.org/stable/c/a2edbb6393972a02114b6003953a5cef3104fada"}, {"url": "https://git.kernel.org/stable/c/1ceeebd5bd6d855b17a5df625109bfe29129d7cf"}, {"url": "https://git.kernel.org/stable/c/86ab3e55673a7a49a841838776f1ab18d23a67b5"}], "title": "ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()", "x_generator": {"engine": "bippy-1.2.0"}}}}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()\n\nSashiko AI-review observed:\n\n In ip6_err_gen_icmpv6_unreach(), the skb is an outer IPv4 ICMP error packet\n where its cb contains an IPv4 inet_skb_parm. When skb is cloned into skb2\n and passed to icmp6_send(), it uses IP6CB(skb2).\n\n IP6CB interprets the IPv4 inet_skb_parm as an inet6_skb_parm. The cipso\n offset in inet_skb_parm.opt directly overlaps with dsthao in inet6_skb_parm\n at offset 18.\n\n If an attacker sends a forged ICMPv4 error with a CIPSO IP option, dsthao\n would be a non-zero offset. Inside icmp6_send(), mip6_addr_swap() is called\n and uses ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO).\n\n This would scan the inner, attacker-controlled IPv6 packet starting at that\n offset, potentially returning a fake TLV without checking if the remaining\n packet length can hold the full 18-byte struct ipv6_destopt_hao.\n\n Could mip6_addr_swap() then perform a 16-byte swap that extends past the end\n of the packet data into skb_shared_info?\n\n Should the cb array also be cleared in ip6_err_gen_icmpv6_unreach() and\n ip6ip6_err() to prevent this?\n\nThis patch implements the first suggestion.\n\nI am not sure if ip6ip6_err() needs to be changed.\nA separate patch would be better anyway."}], "id": "CVE-2026-43038", "lastModified": "2026-05-01T15:24:14.893", "metrics": {}, "published": "2026-05-01T15:16:48.533", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/1ceeebd5bd6d855b17a5df625109bfe29129d7cf"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/3d5127d998de617b130aae96b138dba22ac6a8a7"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/86ab3e55673a7a49a841838776f1ab18d23a67b5"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a2edbb6393972a02114b6003953a5cef3104fada"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a4437faf135da293d16fcc4cc607316742bd0ebb"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/c438ba010171b70bad22fc18b1d5bdc3627476e8"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/e41953e7d118e2702bcb217879c173d9d1d3cd4e"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Awaiting Analysis"}

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