CVE-2026-98852 - Vulnerability Details

Vendors	Products
Linux Subscribe	Linux Kernel Subscribe

Link	Providers
https://git.kernel.org/stable/c/44ba9dc568c878b699d05e7cf699572dc9df4b59
https://git.kernel.org/stable/c/5f0764cb1c81a9712bce605d38efe6d844a70b29
https://git.kernel.org/stable/c/aa480f05aed7a9eee87d4a6fc90647fe9679c670
https://git.kernel.org/stable/c/cabacdf98e09eb74599c4d97d7bd7fd659598fb7

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: net: extend IPv6 exthdr detection of tunneled packets Commit c4336a07eb6b ("net: correctly handle tunneled traffic on IPV6_CSUM GSO fallback") split skb_gso_has_extension_hdr() into mutually exclusive branches on skb->encapsulation. This did not yet address all paths: 1. With skb->encapsulation set, the outer header is not checked. IPv6 tunnels such as ip6_gre and ip6_tunnel add an outer Destination Options header by default (encap_limit). Their GSO packets skip software GSO, then skb_csum_hwoffload_help() sees the outer extension header and calls skb_checksum_help() on the GSO skb, which warns and drops it. 2. Tunnels over IPv6 without an outer transport header, such as ip6_tunnel, leave skb->transport_header at the inner transport header. skb_network_header_len() then spans the outer IPv6, tunnel and inner IP headers, a false positive. 3. UDP tunnels without an inner network header, such as SCTP-in-UDP or PSP, have no inner IPv6 header to check. Decide on the outer header alone. 4. Directly dereferencing inner_ip_hdr(skb)->version without skb_header_pointer() is unsafe. Instead, check ipv6_ext_hdr(nexthdr) on the outer IPv6 header and, if set, on the inner IPv6 header. Read the headers with skb_header_pointer(). Keep the skb_network_header_len() check when !skb->encapsulation to also catch encapsulated packets without skb->encapsulation (e.g., virtio). Use the same helper in skb_csum_hwoffload_help(). Its open coded test has the false positive of (2) and ignores the inner header. Background: checksum offload of tunneled packets invariants: Non-GSO skb: - If the inner packet is CHECKSUM_PARTIAL, Local Checksum Offload computes the outer checksum in software and the device offloads only the inner L4 checksum. - If the inner packet is CHECKSUM_NONE (e.g., SCTP-in-UDP, ESP-in-UDP, Remote Checksum Offload), the device offloads the outer UDP or GRE checksum instead. GSO skb: - A device with NETIF_F_GSO_UDP_TUNNEL_CSUM or NETIF_F_GSO_GRE_CSUM computes both inner and outer checksums per segment. The outer checksum is seeded with only the pseudo-header checksum. A NETIF_F_IPV6_CSUM device must parse through the outer headers to reach the inner ones.
Title		net: extend IPv6 exthdr detection of tunneled packets
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/44ba9dc568c878b699d05e7cf699572dc9df4b59 https://git.kernel.org/stable/c/5f0764cb1c81a9712bce605d38efe6d844a70b29 https://git.kernel.org/stable/c/aa480f05aed7a9eee87d4a6fc90647fe9679c670 https://git.kernel.org/stable/c/cabacdf98e09eb74599c4d97d7bd7fd659598fb7

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-98852", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.376Z", "datePublished": "2026-10-18T15:50:55.946Z", "dateUpdated": "2026-10-18T15:50:55.946Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-18T15:50:55.946Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: extend IPv6 exthdr detection of tunneled packets\n\nCommit c4336a07eb6b (\"net: correctly handle tunneled traffic on IPV6_CSUM\nGSO fallback\") split skb_gso_has_extension_hdr() into mutually exclusive\nbranches on skb->encapsulation. This did not yet address all paths:\n\n1. With skb->encapsulation set, the outer header is not checked. IPv6\n tunnels such as ip6_gre and ip6_tunnel add an outer Destination\n Options header by default (encap_limit). Their GSO packets skip\n software GSO, then skb_csum_hwoffload_help() sees the outer extension\n header and calls skb_checksum_help() on the GSO skb, which warns and\n drops it.\n\n2. Tunnels over IPv6 without an outer transport header, such as\n ip6_tunnel, leave skb->transport_header at the inner transport\n header. skb_network_header_len() then spans the outer IPv6, tunnel\n and inner IP headers, a false positive.\n\n3. UDP tunnels without an inner network header, such as SCTP-in-UDP or\n PSP, have no inner IPv6 header to check. Decide on the outer header\n alone.\n\n4. Directly dereferencing inner_ip_hdr(skb)->version without\n skb_header_pointer() is unsafe.\n\nInstead, check ipv6_ext_hdr(nexthdr) on the outer IPv6 header and, if\nset, on the inner IPv6 header. Read the headers with skb_header_pointer().\nKeep the skb_network_header_len() check when !skb->encapsulation to also\ncatch encapsulated packets without skb->encapsulation (e.g., virtio).\n\nUse the same helper in skb_csum_hwoffload_help(). Its open coded test\nhas the false positive of (2) and ignores the inner header.\n\nBackground: checksum offload of tunneled packets invariants:\n\nNon-GSO skb:\n- If the inner packet is CHECKSUM_PARTIAL, Local Checksum Offload computes\n the outer checksum in software and the device offloads only the inner L4\n checksum.\n- If the inner packet is CHECKSUM_NONE (e.g., SCTP-in-UDP, ESP-in-UDP,\n Remote Checksum Offload), the device offloads the outer UDP or GRE\n checksum instead.\n\nGSO skb:\n- A device with NETIF_F_GSO_UDP_TUNNEL_CSUM or NETIF_F_GSO_GRE_CSUM\n computes both inner and outer checksums per segment.\n The outer checksum is seeded with only the pseudo-header checksum.\n\nA NETIF_F_IPV6_CSUM device must parse through the outer headers to\nreach the inner ones."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/core/dev.c"], "versions": [{"version": "33670f780e0120c3dacda188c512bbffe0b6044c", "lessThan": "44ba9dc568c878b699d05e7cf699572dc9df4b59", "status": "affected", "versionType": "git"}, {"version": "a98b78116a27e2a57b696b569b2cb431c95cf9b6", "lessThan": "aa480f05aed7a9eee87d4a6fc90647fe9679c670", "status": "affected", "versionType": "git"}, {"version": "c4336a07eb6b2526dc2b62928b5104b41a7f81f5", "lessThan": "cabacdf98e09eb74599c4d97d7bd7fd659598fb7", "status": "affected", "versionType": "git"}, {"version": "c4336a07eb6b2526dc2b62928b5104b41a7f81f5", "lessThan": "5f0764cb1c81a9712bce605d38efe6d844a70b29", "status": "affected", "versionType": "git"}, {"version": "2094a7cf91b71367b649f991aacc7b579f793d0b", "status": "affected", "versionType": "git"}, {"version": "ed71cf465c75f5688b07a35d373cd1d6b589c8ea", "status": "affected", "versionType": "git"}, {"version": "732fdeb2987c94b439d51f5cb9addddc2fc48c42", "status": "affected", "versionType": "git"}, {"version": "6.12.81", "lessThan": "6.12.113", "status": "affected", "versionType": "semver"}, {"version": "6.18.22", "lessThan": "6.18.56", "status": "affected", "versionType": "semver"}, {"version": "6.1.168", "lessThan": "6.2", "status": "affected", "versionType": "semver"}, {"version": "6.6.134", "lessThan": "6.7", "status": "affected", "versionType": "semver"}, {"version": "6.19.12", "lessThan": "6.20", "status": "affected", "versionType": "semver"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/core/dev.c"], "versions": [{"version": "7.0", "status": "affected"}, {"version": "0", "lessThan": "7.0", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.113", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.56", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.10", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.3-rc6", "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": "6.12.81", "versionEndExcluding": "6.12.113"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18.22", "versionEndExcluding": "6.18.56"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.0", "versionEndExcluding": "7.2.10"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.0", "versionEndExcluding": "7.3-rc6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1.168"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6.134"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19.12"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/44ba9dc568c878b699d05e7cf699572dc9df4b59"}, {"url": "https://git.kernel.org/stable/c/aa480f05aed7a9eee87d4a6fc90647fe9679c670"}, {"url": "https://git.kernel.org/stable/c/cabacdf98e09eb74599c4d97d7bd7fd659598fb7"}, {"url": "https://git.kernel.org/stable/c/5f0764cb1c81a9712bce605d38efe6d844a70b29"}], "title": "net: extend IPv6 exthdr detection of tunneled packets", "x_generator": {"engine": "bippy-1.2.0"}}}}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/core/dev.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "44ba9dc568c878b699d05e7cf699572dc9df4b59", "status": "affected", "version": "33670f780e0120c3dacda188c512bbffe0b6044c", "versionType": "git"}, {"lessThan": "aa480f05aed7a9eee87d4a6fc90647fe9679c670", "status": "affected", "version": "a98b78116a27e2a57b696b569b2cb431c95cf9b6", "versionType": "git"}, {"lessThan": "cabacdf98e09eb74599c4d97d7bd7fd659598fb7", "status": "affected", "version": "c4336a07eb6b2526dc2b62928b5104b41a7f81f5", "versionType": "git"}, {"lessThan": "5f0764cb1c81a9712bce605d38efe6d844a70b29", "status": "affected", "version": "c4336a07eb6b2526dc2b62928b5104b41a7f81f5", "versionType": "git"}, {"status": "affected", "version": "2094a7cf91b71367b649f991aacc7b579f793d0b", "versionType": "git"}, {"status": "affected", "version": "ed71cf465c75f5688b07a35d373cd1d6b589c8ea", "versionType": "git"}, {"status": "affected", "version": "732fdeb2987c94b439d51f5cb9addddc2fc48c42", "versionType": "git"}, {"lessThan": "6.12.113", "status": "affected", "version": "6.12.81", "versionType": "semver"}, {"lessThan": "6.18.56", "status": "affected", "version": "6.18.22", "versionType": "semver"}, {"lessThan": "6.2", "status": "affected", "version": "6.1.168", "versionType": "semver"}, {"lessThan": "6.7", "status": "affected", "version": "6.6.134", "versionType": "semver"}, {"lessThan": "6.20", "status": "affected", "version": "6.19.12", "versionType": "semver"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/core/dev.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "7.0"}, {"lessThan": "7.0", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.113", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.56", "versionType": "semver"}, {"lessThanOrEqual": "7.2.*", "status": "unaffected", "version": "7.2.10", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.3-rc6", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: extend IPv6 exthdr detection of tunneled packets\n\nCommit c4336a07eb6b (\"net: correctly handle tunneled traffic on IPV6_CSUM\nGSO fallback\") split skb_gso_has_extension_hdr() into mutually exclusive\nbranches on skb->encapsulation. This did not yet address all paths:\n\n1. With skb->encapsulation set, the outer header is not checked. IPv6\n tunnels such as ip6_gre and ip6_tunnel add an outer Destination\n Options header by default (encap_limit). Their GSO packets skip\n software GSO, then skb_csum_hwoffload_help() sees the outer extension\n header and calls skb_checksum_help() on the GSO skb, which warns and\n drops it.\n\n2. Tunnels over IPv6 without an outer transport header, such as\n ip6_tunnel, leave skb->transport_header at the inner transport\n header. skb_network_header_len() then spans the outer IPv6, tunnel\n and inner IP headers, a false positive.\n\n3. UDP tunnels without an inner network header, such as SCTP-in-UDP or\n PSP, have no inner IPv6 header to check. Decide on the outer header\n alone.\n\n4. Directly dereferencing inner_ip_hdr(skb)->version without\n skb_header_pointer() is unsafe.\n\nInstead, check ipv6_ext_hdr(nexthdr) on the outer IPv6 header and, if\nset, on the inner IPv6 header. Read the headers with skb_header_pointer().\nKeep the skb_network_header_len() check when !skb->encapsulation to also\ncatch encapsulated packets without skb->encapsulation (e.g., virtio).\n\nUse the same helper in skb_csum_hwoffload_help(). Its open coded test\nhas the false positive of (2) and ignores the inner header.\n\nBackground: checksum offload of tunneled packets invariants:\n\nNon-GSO skb:\n- If the inner packet is CHECKSUM_PARTIAL, Local Checksum Offload computes\n the outer checksum in software and the device offloads only the inner L4\n checksum.\n- If the inner packet is CHECKSUM_NONE (e.g., SCTP-in-UDP, ESP-in-UDP,\n Remote Checksum Offload), the device offloads the outer UDP or GRE\n checksum instead.\n\nGSO skb:\n- A device with NETIF_F_GSO_UDP_TUNNEL_CSUM or NETIF_F_GSO_GRE_CSUM\n computes both inner and outer checksums per segment.\n The outer checksum is seeded with only the pseudo-header checksum.\n\nA NETIF_F_IPV6_CSUM device must parse through the outer headers to\nreach the inner ones."}], "id": "CVE-2026-98852", "lastModified": "2026-10-18T16:17:39.593", "metrics": {}, "published": "2026-10-18T16:17:39.593", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/44ba9dc568c878b699d05e7cf699572dc9df4b59"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/5f0764cb1c81a9712bce605d38efe6d844a70b29"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/aa480f05aed7a9eee87d4a6fc90647fe9679c670"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/cabacdf98e09eb74599c4d97d7bd7fd659598fb7"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

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