CVE-2026-98570
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: net: ipv6: keep room for the mac header in dst_dev_overhead() The seg6, ioam6 and rpl lwtunnels size their skb_cow_head() request as the length they are about to push plus dst_dev_overhead(), then push the new headers and rebuild the mac header below them with skb_mac_header_rebuild(). That rebuild needs skb->mac_len of headroom, but dst_dev_overhead() leaves LL_RESERVED_SPACE() of the egress device, 16 bytes for plain Ethernet. Where the mac header is longer than that, as it is on ingress through a VLAN device with reorder_hdr off, the rebuild runs out of room: skb_set_mac_header(skb, -skb->mac_len) computes a negative offset, stores it unchecked in the u16 skb->mac_header, and the memmove that follows writes skb->mac_len bytes about 64 KB past skb->head. Forwarding plain ping6 traffic through such a device reproduces it on all five seg6 encapsulation modes and on the rpl and ioam6 inline paths; skb->mac_header comes back as 65534 on a 704-byte head. Return the larger of the two. The helper already returns skb->mac_len when it has no dst, so this only makes the other branch agree, and it covers every caller rather than each call site in turn.
View original CVE JSON
{
"id": "CVE-2026-98570",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-10-18T16:17:09.233",
"lastModified": "2026-10-19T10:19:15.053",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: keep room for the mac header in dst_dev_overhead()\n\nThe seg6, ioam6 and rpl lwtunnels size their skb_cow_head() request as\nthe length they are about to push plus dst_dev_overhead(), then push the\nnew headers and rebuild the mac header below them with\nskb_mac_header_rebuild(). That rebuild needs skb->mac_len of headroom,\nbut dst_dev_overhead() leaves LL_RESERVED_SPACE() of the egress device,\n16 bytes for plain Ethernet.\n\nWhere the mac header is longer than that, as it is on ingress through a\nVLAN device with reorder_hdr off, the rebuild runs out of room:\nskb_set_mac_header(skb, -skb->mac_len) computes a negative offset,\nstores it unchecked in the u16 skb->mac_header, and the memmove that\nfollows writes skb->mac_len bytes about 64 KB past skb->head.\nForwarding plain ping6 traffic through such a device reproduces it on\nall five seg6 encapsulation modes and on the rpl and ioam6 inline paths;\nskb->mac_header comes back as 65534 on a 704-byte head.\n\nReturn the larger of the two. The helper already returns skb->mac_len\nwhen it has no dst, so this only makes the other branch agree, and it\ncovers every caller rather than each call site in turn."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"include/net/dst.h"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "dce525185bc92864e5a318040285ee070563fe34",
"lessThan": "36c07127924f11fc5741a780abcaaf808fe9ef13",
"versionType": "git",
"status": "affected"
},
{
"version": "dce525185bc92864e5a318040285ee070563fe34",
"lessThan": "87cd6b717e4069dca34e0866e57eaeb44d3b173e",
"versionType": "git",
"status": "affected"
},
{
"version": "8471e228448a818e4c27cab4b681b2e758e46cf5",
"versionType": "git",
"status": "affected"
},
{
"version": "c432cd18a07b623651ed15ea167bd303467004cc",
"versionType": "git",
"status": "affected"
},
{
"version": "634710a372ba65bee667c2f6e58a97658c639eab",
"versionType": "git",
"status": "affected"
},
{
"version": "c447c5a9c47bb4858ab12bf90879fe595d2b7f46",
"versionType": "git",
"status": "affected"
},
{
"version": "ab9de9c48316d2622d3bf353916b99971570e2c9",
"versionType": "git",
"status": "affected"
},
{
"version": "2fcc9f3798ef82399564d247458e69abd10e683b",
"versionType": "git",
"status": "affected"
},
{
"version": "371d8dc298b4f59e99b4564ac5d906fce0932c69",
"versionType": "git",
"status": "affected"
},
{
"version": "b26f015dfb07b6be12d005a0ed0c5c43b7bedbf3",
"versionType": "git",
"status": "affected"
},
{
"version": "c0b11dc50590e10590b39dcda79835cd32f49d00",
"versionType": "git",
"status": "affected"
},
{
"version": "4c12c3c8abd8b888945d31e7bdbb0d8b73032fc5",
"versionType": "git",
"status": "affected"
},
{
"version": "25d8e065c7972dc98fd7a4cac322d5367eaede88",
"versionType": "git",
"status": "affected"
},
{
"version": "4a855c5aec41bf84922224ab7a74e088776e3ac4",
"versionType": "git",
"status": "affected"
},
{
"version": "a9f0407414e16176fdbbbd298c9e18d6dfdf96bc",
"versionType": "git",
"status": "affected"
},
{
"version": "6.12.16",
"lessThan": "6.13",
"versionType": "semver",
"status": "affected"
},
{
"version": "6.13.4",
"lessThan": "6.14",
"versionType": "semver",
"status": "affected"
},
{
"version": "5.15.179",
"lessThan": "5.16",
"versionType": "semver",
"status": "affected"
},
{
"version": "6.1.130",
"lessThan": "6.2",
"versionType": "semver",
"status": "affected"
},
{
"version": "6.6.81",
"lessThan": "6.7",
"versionType": "semver",
"status": "affected"
},
{
"version": "5.10.235",
"lessThan": "5.11",
"versionType": "semver",
"status": "affected"
}
]
},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"include/net/dst.h"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "6.14",
"status": "affected"
},
{
"version": "0",
"lessThan": "6.14",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.2.9",
"lessThanOrEqual": "7.2.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {},
"references": [
{
"url": "https://git.kernel.org/stable/c/36c07127924f11fc5741a780abcaaf808fe9ef13",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/87cd6b717e4069dca34e0866e57eaeb44d3b173e",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
]
}