CVE-2026-43038 (GCVE-0-2026-43038)
Vulnerability from cvelistv5 – Published: 2026-05-01 14:15 – Updated: 2026-05-03 05:46
VLAI?
Title
ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()
Summary
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.
Severity ?
9.8 (Critical)
Assigner
References
Impacted products
| Vendor | Product | Version | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux |
Affected:
ca15a078bd907df5fc1c009477869c5cbde3b753 , < c438ba010171b70bad22fc18b1d5bdc3627476e8
(git)
Affected: ca15a078bd907df5fc1c009477869c5cbde3b753 , < 0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7 (git) Affected: ca15a078bd907df5fc1c009477869c5cbde3b753 , < a4437faf135da293d16fcc4cc607316742bd0ebb (git) Affected: ca15a078bd907df5fc1c009477869c5cbde3b753 , < 3d5127d998de617b130aae96b138dba22ac6a8a7 (git) Affected: ca15a078bd907df5fc1c009477869c5cbde3b753 , < e41953e7d118e2702bcb217879c173d9d1d3cd4e (git) Affected: ca15a078bd907df5fc1c009477869c5cbde3b753 , < a2edbb6393972a02114b6003953a5cef3104fada (git) Affected: ca15a078bd907df5fc1c009477869c5cbde3b753 , < 1ceeebd5bd6d855b17a5df625109bfe29129d7cf (git) Affected: ca15a078bd907df5fc1c009477869c5cbde3b753 , < 86ab3e55673a7a49a841838776f1ab18d23a67b5 (git) |
|||||||
|
|||||||||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/ipv6/icmp.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "c438ba010171b70bad22fc18b1d5bdc3627476e8",
"status": "affected",
"version": "ca15a078bd907df5fc1c009477869c5cbde3b753",
"versionType": "git"
},
{
"lessThan": "0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7",
"status": "affected",
"version": "ca15a078bd907df5fc1c009477869c5cbde3b753",
"versionType": "git"
},
{
"lessThan": "a4437faf135da293d16fcc4cc607316742bd0ebb",
"status": "affected",
"version": "ca15a078bd907df5fc1c009477869c5cbde3b753",
"versionType": "git"
},
{
"lessThan": "3d5127d998de617b130aae96b138dba22ac6a8a7",
"status": "affected",
"version": "ca15a078bd907df5fc1c009477869c5cbde3b753",
"versionType": "git"
},
{
"lessThan": "e41953e7d118e2702bcb217879c173d9d1d3cd4e",
"status": "affected",
"version": "ca15a078bd907df5fc1c009477869c5cbde3b753",
"versionType": "git"
},
{
"lessThan": "a2edbb6393972a02114b6003953a5cef3104fada",
"status": "affected",
"version": "ca15a078bd907df5fc1c009477869c5cbde3b753",
"versionType": "git"
},
{
"lessThan": "1ceeebd5bd6d855b17a5df625109bfe29129d7cf",
"status": "affected",
"version": "ca15a078bd907df5fc1c009477869c5cbde3b753",
"versionType": "git"
},
{
"lessThan": "86ab3e55673a7a49a841838776f1ab18d23a67b5",
"status": "affected",
"version": "ca15a078bd907df5fc1c009477869c5cbde3b753",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/ipv6/icmp.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "3.13"
},
{
"lessThan": "3.13",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.253",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.203",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.168",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.134",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.81",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.22",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.19.*",
"status": "unaffected",
"version": "6.19.12",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.0",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.10.253",
"versionStartIncluding": "3.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15.203",
"versionStartIncluding": "3.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.168",
"versionStartIncluding": "3.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.134",
"versionStartIncluding": "3.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.81",
"versionStartIncluding": "3.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.22",
"versionStartIncluding": "3.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.19.12",
"versionStartIncluding": "3.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.0",
"versionStartIncluding": "3.13",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: icmp: clear skb2-\u003ecb[] 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-\u003edsthao, 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."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-05-03T05:46:17.465Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"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-\u003ecb[] in ip6_err_gen_icmpv6_unreach()",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-43038",
"datePublished": "2026-05-01T14:15:35.986Z",
"dateReserved": "2026-05-01T14:12:55.978Z",
"dateUpdated": "2026-05-03T05:46:17.465Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-43038",
"date": "2026-05-08",
"epss": "0.0007",
"percentile": "0.21238"
},
"nvd": "{\"cve\":{\"id\":\"CVE-2026-43038\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-05-01T15:16:48.533\",\"lastModified\":\"2026-05-08T18:47:20.317\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nipv6: icmp: clear skb2-\u003ecb[] 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-\u003edsthao, 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.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":9.8,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":5.9}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"NVD-CWE-noinfo\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartExcluding\":\"3.13\",\"versionEndExcluding\":\"5.10.253\",\"matchCriteriaId\":\"8D3EF93D-D199-4C6C-89F8-AA7C61FD525D\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.11\",\"versionEndExcluding\":\"5.15.203\",\"matchCriteriaId\":\"20DDB3E9-AABF-4107-ADB0-5362AA067045\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.16\",\"versionEndExcluding\":\"6.1.168\",\"matchCriteriaId\":\"E2DDDCA1-6DAB-4018-B920-8F045DDD8D3B\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.2\",\"versionEndExcluding\":\"6.6.134\",\"matchCriteriaId\":\"F56F925B-BAF8-4F4B-B62F-1496AF19A307\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.7\",\"versionEndExcluding\":\"6.12.81\",\"matchCriteriaId\":\"6EF80433-B33B-43C5-8E64-0FA7B8DCE1BC\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.13\",\"versionEndExcluding\":\"6.18.22\",\"matchCriteriaId\":\"C9DF8BCE-36D3-475D-9D21-19E4F02F9029\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.19\",\"versionEndExcluding\":\"6.19.12\",\"matchCriteriaId\":\"0A2B9540-02D5-41B4-B16A-82AF66FD4F36\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:3.13:-:*:*:*:*:*:*\",\"matchCriteriaId\":\"0F72A71E-B6B2-40F2-A21D-BF7CE1514976\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:3.13:rc3:*:*:*:*:*:*\",\"matchCriteriaId\":\"A5F72FE2-8F1D-4C65-889F-38FAB8A28B6D\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:3.13:rc4:*:*:*:*:*:*\",\"matchCriteriaId\":\"C54506BE-8F4B-4411-AEEE-B2C25674B59B\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:3.13:rc5:*:*:*:*:*:*\",\"matchCriteriaId\":\"A4739BC5-112B-4DDA-8921-16A6BFE6AAA7\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:3.13:rc6:*:*:*:*:*:*\",\"matchCriteriaId\":\"5782C96D-D8F7-42C1-A3A0-34B1DEF1FC93\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:3.13:rc7:*:*:*:*:*:*\",\"matchCriteriaId\":\"51B2DAD1-BF87-4AEF-A41D-81B7D042B22A\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:3.13:rc8:*:*:*:*:*:*\",\"matchCriteriaId\":\"C8E94C86-A5D8-4C34-8494-5B471DAEB27A\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*\",\"matchCriteriaId\":\"F253B622-8837-4245-BCE5-A7BF8FC76A16\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*\",\"matchCriteriaId\":\"4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*\",\"matchCriteriaId\":\"F666C8D8-6538-46D4-B318-87610DE64C34\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*\",\"matchCriteriaId\":\"02259FDA-961B-47BC-AE7F-93D7EC6E90C2\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*\",\"matchCriteriaId\":\"58A9FEFF-C040-420D-8F0A-BFDAAA1DF258\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*\",\"matchCriteriaId\":\"1D2315C0-D46F-4F85-9754-F9E5E11374A6\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/1ceeebd5bd6d855b17a5df625109bfe29129d7cf\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/3d5127d998de617b130aae96b138dba22ac6a8a7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/86ab3e55673a7a49a841838776f1ab18d23a67b5\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/a2edbb6393972a02114b6003953a5cef3104fada\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/a4437faf135da293d16fcc4cc607316742bd0ebb\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/c438ba010171b70bad22fc18b1d5bdc3627476e8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/e41953e7d118e2702bcb217879c173d9d1d3cd4e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}"
}
}
Loading…
Loading…
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Loading…
Loading…