{"api_version":"1","generated_at":"2026-09-15T13:15:11+00:00","cve":"CVE-2026-89555","urls":{"html":"https://cve.report/CVE-2026-89555","api":"https://cve.report/api/cve/CVE-2026-89555.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89555","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89555"},"summary":{"title":"mpls: reload header after pskb_may_pull()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmpls: reload header after pskb_may_pull()\n\nmpls_select_multipath() calls mpls_multipath_hash() to choose a nexthop\nwhen an MPLS route has multiple nexthops.  While walking the MPLS label\nstack, the hash routine caches hdr for the current label.  After finding\nthe bottom-of-stack label, it calls pskb_may_pull() before reading the\ninner IP header.\n\nIf an skb is constructed with the inner IP header in nonlinear data and\ninsufficient tailroom in the linear head, pskb_may_pull() calls\npskb_expand_head() to replace the skb head and free the old one.  This\nleaves hdr pointing to freed memory.  The IPv6 path can invalidate hdr\nagain when it performs a second pull for the larger header.\n\nThe issue was found through static analysis.  A reproducer sending a legal\nGeneve packet through a bareudp/MPLS multipath setup triggered the same\nKASAN report in 2 of 2 unpatched runs:\n\n  BUG: KASAN: slab-use-after-free in mpls_select_multipath\n  Read of size 1 at addr ffff88800ecc6e20 by task ksoftirqd/1/23\n\n  Call Trace:\n   mpls_select_multipath\n   mpls_forward\n   __netif_receive_skb_list_core\n   netif_receive_skb_list_internal\n   napi_complete_done\n   gro_cell_poll\n   __napi_poll\n   net_rx_action\n\n  Freed by task 23:\n   kfree\n   pskb_expand_head\n   __pskb_pull_tail\n   mpls_select_multipath\n\nReload hdr from the current skb head after each successful pull before\nderiving the inner IPv4 or IPv6 header pointer.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:19:39","updated_at":"2026-09-14 13:19:10"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"9.8","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","data":{"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"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"9.8","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","data":{"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"}}],"references":[{"url":"https://git.kernel.org/stable/c/d82b90a38c2ca8a0694428eab0e9551c23f2447d","name":"https://git.kernel.org/stable/c/d82b90a38c2ca8a0694428eab0e9551c23f2447d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/49d38c1b4390412f8950d33dfaee0ccbd17beb81","name":"https://git.kernel.org/stable/c/49d38c1b4390412f8950d33dfaee0ccbd17beb81","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/aa4fe0b450a461aa1162fe8375f5d28f4c957df8","name":"https://git.kernel.org/stable/c/aa4fe0b450a461aa1162fe8375f5d28f4c957df8","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/fed638a248116b8a249bd4202d28e5934bdc65ad","name":"https://git.kernel.org/stable/c/fed638a248116b8a249bd4202d28e5934bdc65ad","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/bfaaff99238326166694354a63a76c02563f98b1","name":"https://git.kernel.org/stable/c/bfaaff99238326166694354a63a76c02563f98b1","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/29e63b8d9fc150cc191b1c6eb7e16e1247e1b650","name":"https://git.kernel.org/stable/c/29e63b8d9fc150cc191b1c6eb7e16e1247e1b650","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d9640239827d6d0cb84263b590f7a4f1596c17eb","name":"https://git.kernel.org/stable/c/d9640239827d6d0cb84263b590f7a4f1596c17eb","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b1c0783b2facc398437ad8f8b86c636d7a78f8db","name":"https://git.kernel.org/stable/c/b1c0783b2facc398437ad8f8b86c636d7a78f8db","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89555","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89555","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 9f427a0e474a67b454420c131709600d44850486 aa4fe0b450a461aa1162fe8375f5d28f4c957df8 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 9f427a0e474a67b454420c131709600d44850486 b1c0783b2facc398437ad8f8b86c636d7a78f8db git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 9f427a0e474a67b454420c131709600d44850486 bfaaff99238326166694354a63a76c02563f98b1 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 9f427a0e474a67b454420c131709600d44850486 d9640239827d6d0cb84263b590f7a4f1596c17eb git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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4.10","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 4.10 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.10.270 5.10.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.221 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.188 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.157 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.109 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.50 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.4 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"89555","cve":"CVE-2026-89555","epss":"0.006080000","percentile":"0.472480000","score_date":"2026-09-14","updated_at":"2026-09-15 00:00:41"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/mpls/af_mpls.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"aa4fe0b450a461aa1162fe8375f5d28f4c957df8","status":"affected","version":"9f427a0e474a67b454420c131709600d44850486","versionType":"git"},{"lessThan":"b1c0783b2facc398437ad8f8b86c636d7a78f8db","status":"affected","version":"9f427a0e474a67b454420c131709600d44850486","versionType":"git"},{"lessThan":"bfaaff99238326166694354a63a76c02563f98b1","status":"affected","version":"9f427a0e474a67b454420c131709600d44850486","versionType":"git"},{"lessThan":"d9640239827d6d0cb84263b590f7a4f1596c17eb","status":"affected","version":"9f427a0e474a67b454420c131709600d44850486","versionType":"git"},{"lessThan":"fed638a248116b8a249bd4202d28e5934bdc65ad","status":"affected","version":"9f427a0e474a67b454420c131709600d44850486","versionType":"git"},{"lessThan":"d82b90a38c2ca8a0694428eab0e9551c23f2447d","status":"affected","version":"9f427a0e474a67b454420c131709600d44850486","versionType":"git"},{"lessThan":"49d38c1b4390412f8950d33dfaee0ccbd17beb81","status":"affected","version":"9f427a0e474a67b454420c131709600d44850486","versionType":"git"},{"lessThan":"29e63b8d9fc150cc191b1c6eb7e16e1247e1b650","status":"affected","version":"9f427a0e474a67b454420c131709600d44850486","versionType":"git"},{"status":"affected","version":"ad864d9fce0ec56cc8f6afe5c6a0e6d7f484b9eb","versionType":"git"},{"lessThan":"4.10","status":"affected","version":"4.9.8","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/mpls/af_mpls.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"4.10"},{"lessThan":"4.10","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.270","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.221","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.188","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.157","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.109","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.50","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.4","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.10.270","versionStartIncluding":"4.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.221","versionStartIncluding":"4.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.188","versionStartIncluding":"4.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.157","versionStartIncluding":"4.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.109","versionStartIncluding":"4.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.50","versionStartIncluding":"4.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","versionStartIncluding":"4.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"4.10","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9.8","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmpls: reload header after pskb_may_pull()\n\nmpls_select_multipath() calls mpls_multipath_hash() to choose a nexthop\nwhen an MPLS route has multiple nexthops.  While walking the MPLS label\nstack, the hash routine caches hdr for the current label.  After finding\nthe bottom-of-stack label, it calls pskb_may_pull() before reading the\ninner IP header.\n\nIf an skb is constructed with the inner IP header in nonlinear data and\ninsufficient tailroom in the linear head, pskb_may_pull() calls\npskb_expand_head() to replace the skb head and free the old one.  This\nleaves hdr pointing to freed memory.  The IPv6 path can invalidate hdr\nagain when it performs a second pull for the larger header.\n\nThe issue was found through static analysis.  A reproducer sending a legal\nGeneve packet through a bareudp/MPLS multipath setup triggered the same\nKASAN report in 2 of 2 unpatched runs:\n\n  BUG: KASAN: slab-use-after-free in mpls_select_multipath\n  Read of size 1 at addr ffff88800ecc6e20 by task ksoftirqd/1/23\n\n  Call Trace:\n   mpls_select_multipath\n   mpls_forward\n   __netif_receive_skb_list_core\n   netif_receive_skb_list_internal\n   napi_complete_done\n   gro_cell_poll\n   __napi_poll\n   net_rx_action\n\n  Freed by task 23:\n   kfree\n   pskb_expand_head\n   __pskb_pull_tail\n   mpls_select_multipath\n\nReload hdr from the current skb head after each successful pull before\nderiving the inner IPv4 or IPv6 header pointer."}],"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"},"scenarios":[{"lang":"en","value":"AV:N - mpls_forward() is the ETH_P_MPLS_UC packet_type receive handler; remote MPLS-in-IP (IPPROTO_MPLS), MPLS-over-UDP/bareudp, Geneve, and IPIP/SIT/ip6 tunnels deliver inner MPLS into this path without local access, matching the Geneve/bareudp KASAN reproducer.\nAC:L - An attacker sending MPLS or tunneled overlay frames fully controls the label stack, BOS bit, and skb layout; GRO/tunnel decap yields nonlinear skbs so pskb_may_pull() reallocates skb->head, and the unpatched Geneve reproducer hit the UAF in 2 of 2 runs with no victim-timed race.\nPR:N - Exploitation needs only unauthenticated packets that hit an already configured MPLS-enabled interface and multipath label route; mpls_forward() performs no credential check, and enabling MPLS input or tunnels is victim deployment rather than an attacker privilege.\nUI:N - The use-after-free runs in softirq receive processing (gro_cell_poll / netif_receive_skb_list) as soon as the crafted frame is accepted; no local user or administrator action is required beyond normal forwarding.\nS:U - The stale MPLS header pointer is a heap use-after-free inside the same host kernel MPLS forwarding path; impact stays within that kernel security authority and does not cross a VM, IOMMU, or other boundary.\nC:H - After pskb_expand_head() frees the old skb head, mpls_multipath_hash() reads the inner IPv4/IPv6 header through the stale hdr pointer, a slab use-after-free that can disclose freed kmalloc contents and is scored as high-impact kernel information disclosure.\nI:H - The immediate stale access is a header read used for ECMP hashing, but it remains a kernel slab use-after-free of skb->head; attacker-controlled reclaim of the freed kmalloc object is a well-established path to heap corruption and control-flow hijacking.\nA:H - KASAN confirmed a slab-use-after-free in mpls_select_multipath() on the forwarding path; dereferencing the freed skb head can oops or panic the kernel, and UAFs remain a high-impact denial of service even without full exploitation."}]}],"providerMetadata":{"dateUpdated":"2026-09-14T12:00:57.921Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/aa4fe0b450a461aa1162fe8375f5d28f4c957df8"},{"url":"https://git.kernel.org/stable/c/b1c0783b2facc398437ad8f8b86c636d7a78f8db"},{"url":"https://git.kernel.org/stable/c/bfaaff99238326166694354a63a76c02563f98b1"},{"url":"https://git.kernel.org/stable/c/d9640239827d6d0cb84263b590f7a4f1596c17eb"},{"url":"https://git.kernel.org/stable/c/fed638a248116b8a249bd4202d28e5934bdc65ad"},{"url":"https://git.kernel.org/stable/c/d82b90a38c2ca8a0694428eab0e9551c23f2447d"},{"url":"https://git.kernel.org/stable/c/49d38c1b4390412f8950d33dfaee0ccbd17beb81"},{"url":"https://git.kernel.org/stable/c/29e63b8d9fc150cc191b1c6eb7e16e1247e1b650"}],"title":"mpls: reload header after pskb_may_pull()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89555","datePublished":"2026-09-11T19:44:28.331Z","dateReserved":"2026-09-11T19:38:34.724Z","dateUpdated":"2026-09-14T12:00:57.921Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:19:39","lastModifiedDate":"2026-09-14 13:19:10","problem_types":[],"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}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89555","Ordinal":"1","Title":"mpls: reload header after pskb_may_pull()","CVE":"CVE-2026-89555","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89555","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nmpls: reload header after pskb_may_pull()\n\nmpls_select_multipath() calls mpls_multipath_hash() to choose a nexthop\nwhen an MPLS route has multiple nexthops.  While walking the MPLS label\nstack, the hash routine caches hdr for the current label.  After finding\nthe bottom-of-stack label, it calls pskb_may_pull() before reading the\ninner IP header.\n\nIf an skb is constructed with the inner IP header in nonlinear data and\ninsufficient tailroom in the linear head, pskb_may_pull() calls\npskb_expand_head() to replace the skb head and free the old one.  This\nleaves hdr pointing to freed memory.  The IPv6 path can invalidate hdr\nagain when it performs a second pull for the larger header.\n\nThe issue was found through static analysis.  A reproducer sending a legal\nGeneve packet through a bareudp/MPLS multipath setup triggered the same\nKASAN report in 2 of 2 unpatched runs:\n\n  BUG: KASAN: slab-use-after-free in mpls_select_multipath\n  Read of size 1 at addr ffff88800ecc6e20 by task ksoftirqd/1/23\n\n  Call Trace:\n   mpls_select_multipath\n   mpls_forward\n   __netif_receive_skb_list_core\n   netif_receive_skb_list_internal\n   napi_complete_done\n   gro_cell_poll\n   __napi_poll\n   net_rx_action\n\n  Freed by task 23:\n   kfree\n   pskb_expand_head\n   __pskb_pull_tail\n   mpls_select_multipath\n\nReload hdr from the current skb head after each successful pull before\nderiving the inner IPv4 or IPv6 header pointer.","Type":"Description","Title":"mpls: reload header after pskb_may_pull()"}]}}}