{"id":"CVE-2026-89555","summary":"mpls: reload header after pskb_may_pull()","details":"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.","modified":"2026-09-13T03:47:19.163454464Z","published":"2026-09-11T19:44:28.331Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89555.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/29e63b8d9fc150cc191b1c6eb7e16e1247e1b650"},{"type":"WEB","url":"https://git.kernel.org/stable/c/49d38c1b4390412f8950d33dfaee0ccbd17beb81"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d82b90a38c2ca8a0694428eab0e9551c23f2447d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fed638a248116b8a249bd4202d28e5934bdc65ad"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89555.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89555"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"9f427a0e474a67b454420c131709600d44850486"},{"fixed":"fed638a248116b8a249bd4202d28e5934bdc65ad"},{"fixed":"d82b90a38c2ca8a0694428eab0e9551c23f2447d"},{"fixed":"49d38c1b4390412f8950d33dfaee0ccbd17beb81"},{"fixed":"29e63b8d9fc150cc191b1c6eb7e16e1247e1b650"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0"},{"last_affected":"ad864d9fce0ec56cc8f6afe5c6a0e6d7f484b9eb"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"4.9.8"},{"fixed":"4.10"}]}],"versions":["v4.9","v4.9.7","v4.9.6","v4.9.5","v4.9.4","v4.9.3","v4.9.2","v4.9.1","v4.9-rc7","v4.9-rc6","v4.9-rc8","v4.9-rc1","v4.9-rc5","v4.9-rc3","v4.9-rc4","v4.9-rc2","v4.8","v4.8-rc8","v4.8-rc2","v4.8-rc1","v4.8-rc7","v4.8-rc6","v4.8-rc5","v4.8-rc4","v4.8-rc3","v4.7","v4.7-rc4","v4.7-rc2","v4.7-rc1","v4.7-rc7","v4.7-rc6","v4.7-rc3","v4.7-rc5","v4.6","v4.6-rc1","v4.6-rc6","v4.6-rc4","v4.6-rc7","v4.6-rc5","v4.5-rc4","v4.6-rc2","v4.6-rc3","v4.5","v4.4","v4.5-rc1","v4.5-rc6","v4.5-rc2","v4.5-rc7","v4.5-rc5","v4.5-rc3","v4.4-rc1","v4.4-rc2","v4.4-rc8","v4.4-rc3","v4.4-rc7","v4.4-rc5","v4.4-rc6","v4.4-rc4","v4.3","v4.3-rc1","v4.3-rc6","v4.3-rc4","v4.3-rc2","v4.3-rc7","v4.3-rc5","v4.3-rc3","v4.2","v4.2-rc2","v4.2-rc1","v4.2-rc8","v4.2-rc4","v4.2-rc6","v4.2-rc7","v4.0-rc5","v4.2-rc5","v4.2-rc3","v4.1-rc2","v4.1","v4.1-rc1","v4.1-rc8","v4.1-rc7","v4.1-rc6","v4.1-rc3","v4.1-rc4","v4.0","v4.1-rc5","v4.0-rc1","v4.0-rc2","v4.0-rc7","v4.0-rc3","v4.0-rc6","v4.0-rc4","v3.19","v3.19-rc7","v3.19-rc5","v3.19-rc1","v3.19-rc6","v3.19-rc4","v3.18-rc1","v3.19-rc3","v3.19-rc2","v3.18","v3.18-rc7","v3.18-rc6","v3.18-rc2","v3.18-rc3","v3.18-rc4","v3.18-rc5","v3.17","v3.17-rc1","v3.17-rc7","v3.17-rc2","v3.17-rc4","v3.16","v3.17-rc5","v3.17-rc6","v3.17-rc3","v3.16-rc7","v3.16-rc1","v3.16-rc3","v3.16-rc5","v3.16-rc6","v3.16-rc2","v3.16-rc4","v3.13","v3.15","v3.15-rc5","v3.15-rc8","v3.15-rc1","v3.15-rc6","v3.15-rc3","v3.15-rc7","v3.15-rc2","v3.15-rc4","v3.14","v3.14-rc4","v3.14-rc8","v3.14-rc7","v3.14-rc6","v3.14-rc1","v3.14-rc2","v3.14-rc5","v3.14-rc3","v3.13-rc6","v3.13-rc8","v3.12","v3.13-rc7","v3.13-rc1","v3.13-rc4","v3.13-rc3","v3.13-rc5","v3.13-rc2","v3.12-rc7","v3.12-rc3","v3.12-rc6","v3.12-rc1","v3.12-rc5","v3.11","v3.12-rc2","v3.12-rc4","v3.11-rc7","v3.11-rc2","v3.11-rc5","v3.11-rc1","v3.11-rc3","v3.11-rc4","v3.11-rc6","v3.10-rc2","v3.10","v3.10-rc7","v3.10-rc6","v3.10-rc1","v3.10-rc5","v3.10-rc3","v3.10-rc4","v3.9","v3.9-rc2","v3.9-rc7","v3.9-rc8","v3.9-rc3","v3.9-rc6","v3.9-rc5","v3.9-rc4","v3.9-rc1","v3.8","v3.8-rc7","v3.8-rc6","v3.8-rc5","v3.8-rc2","v3.8-rc1","v3.8-rc3","v3.8-rc4","v3.7","v3.7-rc1","v3.6","v3.7-rc6","v3.7-rc7","v3.7-rc3","v3.7-rc8","v3.7-rc2","v3.7-rc4","v3.7-rc5","v3.6-rc7","v3.6-rc1","v3.5-rc3","v3.6-rc6","v3.6-rc5","v3.5","v3.6-rc3","v3.6-rc4","v3.6-rc2","v3.4-rc4","v3.5-rc7","v3.5-rc5","v3.5-rc6","v3.5-rc2","v3.5-rc1","v3.5-rc4","v3.4","v3.4-rc2","v3.4-rc1","v3.4-rc7","v3.4-rc6","v3.4-rc3","v3.4-rc5","v3.3","v3.3-rc6","v3.3-rc3","v3.3-rc7","v3.3-rc2","v3.3-rc5","v3.2","v3.3-rc4","v3.3-rc1","v3.2-rc4","v3.2-rc7","v3.2-rc6","v3.2-rc5","v3.2-rc3","v3.1","v3.2-rc2","v3.2-rc1","v3.1-rc1","v3.1-rc9","v3.1-rc8","v3.1-rc10","v3.1-rc7","v3.1-rc3","v3.1-rc2","v3.1-rc4","v3.1-rc5","v3.0","v3.1-rc6","v3.0-rc7","v3.0-rc4","v3.0-rc6","v3.0-rc5","v3.0-rc3","v3.0-rc1","v2.6.39","v3.0-rc2","v2.6.38","v2.6.39-rc2","v2.6.39-rc7","v2.6.39-rc5","v2.6.39-rc1","v2.6.38-rc7","v2.6.39-rc6","v2.6.39-rc4","v2.6.39-rc3","v2.6.37","v2.6.38-rc1","v2.6.38-rc8","v2.6.38-rc2","v2.6.38-rc6","v2.6.38-rc5","v2.6.38-rc4","v2.6.38-rc3","v2.6.37-rc4","v2.6.37-rc2","v2.6.36","v2.6.37-rc5","v2.6.37-rc8","v2.6.37-rc7","v2.6.37-rc6","v2.6.37-rc1","v2.6.37-rc3","v2.6.36-rc6","v2.6.35-rc4","v2.6.36-rc8","v2.6.35","v2.6.36-rc7","v2.6.36-rc3","v2.6.36-rc5","v2.6.36-rc4","v2.6.36-rc2","v2.6.36-rc1","v2.6.35-rc5","v2.6.35-rc6","v2.6.34",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