CVE-2026-99191 - Vulnerability Details

Vendors	Products
Linux	Linux Linux Kernel

Link	Providers
https://git.kernel.org/stable/c/1c9fcfca51e3c5cd46dd72a4da74d56eff183513
https://git.kernel.org/stable/c/8070ed578b6b9134e045627fb745c887a806d46e
https://git.kernel.org/stable/c/8ee0e03663826a76507048d58466b29321a57656

Type	Values Removed	Values Added
First Time appeared		Linux linux
Vendors & Products		Linux linux

Type	Values Removed	Values Added
Weaknesses		CWE-190

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: calipso: keep BIG TCP payload_len in calipso_skbuff_setattr() calipso_skbuff_setattr() adjusts payload_len by the length of the option it inserts or resizes: payload = ntohs(ip6_hdr->payload_len); ip6_hdr->payload_len = htons(payload + len_delta); GRO can build BIG TCP packets larger than IPV6_MAXPLEN, and stores payload_len == 0 for them; ipv6_payload_len() then falls back to skb->len. For such a packet forwarded to a destination mapped to CALIPSO, the code above writes len_delta (or 65536 + len_delta when shrinking) into payload_len, and ipv6_payload_len() no longer falls back to skb->len. nf_tables, conntrack and sch_cake rely on it. The same arithmetic also wraps when a packet grows past IPV6_MAXPLEN, and a BIG TCP packet that shrinks below IPV6_MAXPLEN should get its real length back. Set payload_len from the skb length with ipv6_set_payload_len(), which stores 0 above IPV6_MAXPLEN and the real length otherwise, as ipv6_gro_complete() does. The network header was just reset to skb->data, so skb->len - sizeof(*ip6_hdr) is the payload length. Tested on one kernel (arm64, QEMU) with SELinux permissive, a minimal mdp-generated policy (network_peer_controls=1), "netlabelctl calipso add pass doi:16" and a NetLabel mapping of fd00:2::/64 to CALIPSO DOI 16. calipso_skbuff_setattr() was called through netlbl_skbuff_setattr() from a test-only debugfs hook (not part of this patch) adding a level-only label; payload_len after the call: case before fix after fix real length 1000, unlabeled 1016 1016 1016 70000 GSO, payload_len 0 16 0 70016 65530 GSO, grows past MAXPLEN 10 0 65546 65540 GSO with a 24 byte hop header, shrinks below MAXPLEN 65528 65532 65532 1000 with a 24 byte hop header 992 992 992 (0 means ipv6_payload_len() returns the real length.) On the forward path, with a client injecting unlabeled UDP through a router to a server, the router adds the CALIPSO option and the server delivers all datagrams (Udp6InDatagrams 5, Ip6InTruncatedPkts 0) with this patch.
Title		calipso: keep BIG TCP payload_len in calipso_skbuff_setattr()
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/1c9fcfca51e3c5cd46dd72a4da74d56eff183513 https://git.kernel.org/stable/c/8070ed578b6b9134e045627fb745c887a806d46e https://git.kernel.org/stable/c/8ee0e03663826a76507048d58466b29321a57656

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-99191", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.400Z", "datePublished": "2026-10-28T10:35:47.854Z", "dateUpdated": "2026-10-28T10:35:47.854Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-28T10:35:47.854Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncalipso: keep BIG TCP payload_len in calipso_skbuff_setattr()\n\ncalipso_skbuff_setattr() adjusts payload_len by the length of the\noption it inserts or resizes:\n\n\tpayload = ntohs(ip6_hdr->payload_len);\n\tip6_hdr->payload_len = htons(payload + len_delta);\n\nGRO can build BIG TCP packets larger than IPV6_MAXPLEN, and stores\npayload_len == 0 for them; ipv6_payload_len() then falls back to\nskb->len. For such a packet forwarded to a destination mapped to\nCALIPSO, the code above writes len_delta (or 65536 + len_delta when\nshrinking) into payload_len, and ipv6_payload_len() no longer falls\nback to skb->len. nf_tables, conntrack and sch_cake rely on it.\n\nThe same arithmetic also wraps when a packet grows past IPV6_MAXPLEN,\nand a BIG TCP packet that shrinks below IPV6_MAXPLEN should get its\nreal length back.\n\nSet payload_len from the skb length with ipv6_set_payload_len(), which\nstores 0 above IPV6_MAXPLEN and the real length otherwise, as\nipv6_gro_complete() does. The network header was just reset to\nskb->data, so skb->len - sizeof(*ip6_hdr) is the payload length.\n\nTested on one kernel (arm64, QEMU) with SELinux permissive, a minimal\nmdp-generated policy (network_peer_controls=1), \"netlabelctl calipso\nadd pass doi:16\" and a NetLabel mapping of fd00:2::/64 to CALIPSO\nDOI 16. calipso_skbuff_setattr() was called through\nnetlbl_skbuff_setattr() from a test-only debugfs hook (not part of\nthis patch) adding a level-only label; payload_len after the call:\n\n case before fix after fix real length\n 1000, unlabeled 1016 1016 1016\n 70000 GSO, payload_len 0 16 0 70016\n 65530 GSO, grows past MAXPLEN 10 0 65546\n 65540 GSO with a 24 byte hop\n header, shrinks below MAXPLEN 65528 65532 65532\n 1000 with a 24 byte hop header 992 992 992\n\n(0 means ipv6_payload_len() returns the real length.) On the forward\npath, with a client injecting unlabeled UDP through a router to a\nserver, the router adds the CALIPSO option and the server delivers all\ndatagrams (Udp6InDatagrams 5, Ip6InTruncatedPkts 0) with this patch."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/ipv6/calipso.c"], "versions": [{"version": "81fbc812132cbc72a0f933b19bfd3a829bd946e4", "lessThan": "1c9fcfca51e3c5cd46dd72a4da74d56eff183513", "status": "affected", "versionType": "git"}, {"version": "81fbc812132cbc72a0f933b19bfd3a829bd946e4", "lessThan": "8ee0e03663826a76507048d58466b29321a57656", "status": "affected", "versionType": "git"}, {"version": "81fbc812132cbc72a0f933b19bfd3a829bd946e4", "lessThan": "8070ed578b6b9134e045627fb745c887a806d46e", "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/calipso.c"], "versions": [{"version": "5.19", "status": "affected"}, {"version": "0", "lessThan": "5.19", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.59", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.13", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.3", "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": "5.19", "versionEndExcluding": "6.18.59"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "7.2.13"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "7.3"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/1c9fcfca51e3c5cd46dd72a4da74d56eff183513"}, {"url": "https://git.kernel.org/stable/c/8ee0e03663826a76507048d58466b29321a57656"}, {"url": "https://git.kernel.org/stable/c/8070ed578b6b9134e045627fb745c887a806d46e"}], "title": "calipso: keep BIG TCP payload_len in calipso_skbuff_setattr()", "x_generator": {"engine": "bippy-1.2.0"}}}}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/ipv6/calipso.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "1c9fcfca51e3c5cd46dd72a4da74d56eff183513", "status": "affected", "version": "81fbc812132cbc72a0f933b19bfd3a829bd946e4", "versionType": "git"}, {"lessThan": "8ee0e03663826a76507048d58466b29321a57656", "status": "affected", "version": "81fbc812132cbc72a0f933b19bfd3a829bd946e4", "versionType": "git"}, {"lessThan": "8070ed578b6b9134e045627fb745c887a806d46e", "status": "affected", "version": "81fbc812132cbc72a0f933b19bfd3a829bd946e4", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/ipv6/calipso.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "5.19"}, {"lessThan": "5.19", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.59", "versionType": "semver"}, {"lessThanOrEqual": "7.2.*", "status": "unaffected", "version": "7.2.13", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.3", "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\ncalipso: keep BIG TCP payload_len in calipso_skbuff_setattr()\n\ncalipso_skbuff_setattr() adjusts payload_len by the length of the\noption it inserts or resizes:\n\n\tpayload = ntohs(ip6_hdr->payload_len);\n\tip6_hdr->payload_len = htons(payload + len_delta);\n\nGRO can build BIG TCP packets larger than IPV6_MAXPLEN, and stores\npayload_len == 0 for them; ipv6_payload_len() then falls back to\nskb->len. For such a packet forwarded to a destination mapped to\nCALIPSO, the code above writes len_delta (or 65536 + len_delta when\nshrinking) into payload_len, and ipv6_payload_len() no longer falls\nback to skb->len. nf_tables, conntrack and sch_cake rely on it.\n\nThe same arithmetic also wraps when a packet grows past IPV6_MAXPLEN,\nand a BIG TCP packet that shrinks below IPV6_MAXPLEN should get its\nreal length back.\n\nSet payload_len from the skb length with ipv6_set_payload_len(), which\nstores 0 above IPV6_MAXPLEN and the real length otherwise, as\nipv6_gro_complete() does. The network header was just reset to\nskb->data, so skb->len - sizeof(*ip6_hdr) is the payload length.\n\nTested on one kernel (arm64, QEMU) with SELinux permissive, a minimal\nmdp-generated policy (network_peer_controls=1), \"netlabelctl calipso\nadd pass doi:16\" and a NetLabel mapping of fd00:2::/64 to CALIPSO\nDOI 16. calipso_skbuff_setattr() was called through\nnetlbl_skbuff_setattr() from a test-only debugfs hook (not part of\nthis patch) adding a level-only label; payload_len after the call:\n\n case before fix after fix real length\n 1000, unlabeled 1016 1016 1016\n 70000 GSO, payload_len 0 16 0 70016\n 65530 GSO, grows past MAXPLEN 10 0 65546\n 65540 GSO with a 24 byte hop\n header, shrinks below MAXPLEN 65528 65532 65532\n 1000 with a 24 byte hop header 992 992 992\n\n(0 means ipv6_payload_len() returns the real length.) On the forward\npath, with a client injecting unlabeled UDP through a router to a\nserver, the router adds the CALIPSO option and the server delivers all\ndatagrams (Udp6InDatagrams 5, Ip6InTruncatedPkts 0) with this patch."}], "id": "CVE-2026-99191", "lastModified": "2026-10-28T11:17:40.080", "metrics": {}, "published": "2026-10-28T11:17:40.080", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/1c9fcfca51e3c5cd46dd72a4da74d56eff183513"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/8070ed578b6b9134e045627fb745c887a806d46e"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/8ee0e03663826a76507048d58466b29321a57656"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

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