{"id":"CVE-2026-98570","state":"PUBLISHED","title":"net: ipv6: keep room for the mac header in dst_dev_overhead()","description":"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.","publishedAt":"2026-10-18T15:18:36.308Z","updatedAt":"2026-10-19T09:21:55.765Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"dce525185bc92864e5a318040285ee070563fe34","status":"affected","lessThan":"36c07127924f11fc5741a780abcaaf808fe9ef13","versionType":"git"},{"version":"dce525185bc92864e5a318040285ee070563fe34","status":"affected","lessThan":"87cd6b717e4069dca34e0866e57eaeb44d3b173e","versionType":"git"},{"version":"8471e228448a818e4c27cab4b681b2e758e46cf5","status":"affected","versionType":"git"},{"version":"c432cd18a07b623651ed15ea167bd303467004cc","status":"affected","versionType":"git"},{"version":"634710a372ba65bee667c2f6e58a97658c639eab","status":"affected","versionType":"git"},{"version":"c447c5a9c47bb4858ab12bf90879fe595d2b7f46","status":"affected","versionType":"git"},{"version":"ab9de9c48316d2622d3bf353916b99971570e2c9","status":"affected","versionType":"git"},{"version":"2fcc9f3798ef82399564d247458e69abd10e683b","status":"affected","versionType":"git"},{"version":"371d8dc298b4f59e99b4564ac5d906fce0932c69","status":"affected","versionType":"git"},{"version":"b26f015dfb07b6be12d005a0ed0c5c43b7bedbf3","status":"affected","versionType":"git"},{"version":"c0b11dc50590e10590b39dcda79835cd32f49d00","status":"affected","versionType":"git"},{"version":"4c12c3c8abd8b888945d31e7bdbb0d8b73032fc5","status":"affected","versionType":"git"},{"version":"25d8e065c7972dc98fd7a4cac322d5367eaede88","status":"affected","versionType":"git"},{"version":"4a855c5aec41bf84922224ab7a74e088776e3ac4","status":"affected","versionType":"git"},{"version":"a9f0407414e16176fdbbbd298c9e18d6dfdf96bc","status":"affected","versionType":"git"},{"version":"6.12.16","status":"affected","lessThan":"6.13","versionType":"semver"},{"version":"6.13.4","status":"affected","lessThan":"6.14","versionType":"semver"},{"version":"5.15.179","status":"affected","lessThan":"5.16","versionType":"semver"},{"version":"6.1.130","status":"affected","lessThan":"6.2","versionType":"semver"},{"version":"6.6.81","status":"affected","lessThan":"6.7","versionType":"semver"},{"version":"5.10.235","status":"affected","lessThan":"5.11","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/dst.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.14","versionType":"semver"},{"version":"7.2.9","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/dst.h"]}],"references":["https://git.kernel.org/stable/c/36c07127924f11fc5741a780abcaaf808fe9ef13","https://git.kernel.org/stable/c/87cd6b717e4069dca34e0866e57eaeb44d3b173e"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/98xxx/CVE-2026-98570.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98570","state":"PUBLISHED","datePublished":"2026-10-18T15:18:36.308Z","dateUpdated":"2026-10-19T09:21:55.765Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.357Z"},"containers":{"cna":{"title":"net: ipv6: keep room for the mac header in dst_dev_overhead()","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":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"dce525185bc92864e5a318040285ee070563fe34","status":"affected","lessThan":"36c07127924f11fc5741a780abcaaf808fe9ef13","versionType":"git"},{"version":"dce525185bc92864e5a318040285ee070563fe34","status":"affected","lessThan":"87cd6b717e4069dca34e0866e57eaeb44d3b173e","versionType":"git"},{"version":"8471e228448a818e4c27cab4b681b2e758e46cf5","status":"affected","versionType":"git"},{"version":"c432cd18a07b623651ed15ea167bd303467004cc","status":"affected","versionType":"git"},{"version":"634710a372ba65bee667c2f6e58a97658c639eab","status":"affected","versionType":"git"},{"version":"c447c5a9c47bb4858ab12bf90879fe595d2b7f46","status":"affected","versionType":"git"},{"version":"ab9de9c48316d2622d3bf353916b99971570e2c9","status":"affected","versionType":"git"},{"version":"2fcc9f3798ef82399564d247458e69abd10e683b","status":"affected","versionType":"git"},{"version":"371d8dc298b4f59e99b4564ac5d906fce0932c69","status":"affected","versionType":"git"},{"version":"b26f015dfb07b6be12d005a0ed0c5c43b7bedbf3","status":"affected","versionType":"git"},{"version":"c0b11dc50590e10590b39dcda79835cd32f49d00","status":"affected","versionType":"git"},{"version":"4c12c3c8abd8b888945d31e7bdbb0d8b73032fc5","status":"affected","versionType":"git"},{"version":"25d8e065c7972dc98fd7a4cac322d5367eaede88","status":"affected","versionType":"git"},{"version":"4a855c5aec41bf84922224ab7a74e088776e3ac4","status":"affected","versionType":"git"},{"version":"a9f0407414e16176fdbbbd298c9e18d6dfdf96bc","status":"affected","versionType":"git"},{"version":"6.12.16","status":"affected","lessThan":"6.13","versionType":"semver"},{"version":"6.13.4","status":"affected","lessThan":"6.14","versionType":"semver"},{"version":"5.15.179","status":"affected","lessThan":"5.16","versionType":"semver"},{"version":"6.1.130","status":"affected","lessThan":"6.2","versionType":"semver"},{"version":"6.6.81","status":"affected","lessThan":"6.7","versionType":"semver"},{"version":"5.10.235","status":"affected","lessThan":"5.11","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/dst.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.14","versionType":"semver"},{"version":"7.2.9","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/dst.h"]}],"references":[{"url":"https://git.kernel.org/stable/c/36c07127924f11fc5741a780abcaaf808fe9ef13"},{"url":"https://git.kernel.org/stable/c/87cd6b717e4069dca34e0866e57eaeb44d3b173e"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T09:21:55.765Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.14","versionEndExcluding":"7.2.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.14","versionEndExcluding":"7.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12.16"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15.179"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1.130"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6.81"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12.16"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10.235"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15.179"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1.130"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6.81"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12.16"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13.4"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}