{"id":21477,"date":"2026-09-12T04:31:14","date_gmt":"2026-09-11T20:31:14","guid":{"rendered":"https:\/\/www.54iter.cn\/?vuln=cve-2026-89555"},"modified":"2026-09-12T04:31:14","modified_gmt":"2026-09-11T20:31:14","slug":"cve-2026-89555","status":"publish","type":"vuln","link":"https:\/\/www.54iter.cn\/?vuln=cve-2026-89555","title":{"rendered":"CVE-2026-89555 &#8211; In the Linux kernel, the following vulnerability has been resolved:\n\nmpls: reload header a"},"content":{"rendered":"<p>In the Linux kernel, the following vulnerability has been resolved:<\/p>\n<p>mpls: reload header after pskb_may_pull()<\/p>\n<p>mpls_select_multipath() calls mpls_multipath_hash() to choose a nexthop<br \/>\nwhen an MPLS route has multiple nexthops.  While walking the MPLS label<br \/>\nstack, the hash routine caches hdr for the current label.  After finding<br \/>\nthe bottom-of-stack label, it calls pskb_may_pull() before reading the<br \/>\ninner IP header.<\/p>\n<p>If an skb is constructed with the inner IP header in nonlinear data and<br \/>\ninsufficient tailroom in the linear head, pskb_may_pull() calls<br \/>\npskb_expand_head() to replace the skb head and free the old one.  This<br \/>\nleaves hdr pointing to freed memory.  The IPv6 path can invalidate hdr<br \/>\nagain when it performs a second pull for the larger header.<\/p>\n<p>The issue was found through static analysis.  A reproducer sending a legal<br \/>\nGeneve packet through a bareudp\/MPLS multipath setup triggered the same<br \/>\nKASAN report in 2 of 2 unpatched runs:<\/p>\n<p>  BUG: KASAN: slab-use-after-free in mpls_select_multipath<br \/>\n  Read of size 1 at addr ffff88800ecc6e20 by task ksoftirqd\/1\/23<\/p>\n<p>  Call Trace:<br \/>\n   mpls_select_multipath<br \/>\n   mpls_forward<br \/>\n   __netif_receive_skb_list_core<br \/>\n   netif_receive_skb_list_internal<br \/>\n   napi_complete_done<br \/>\n   gro_cell_poll<br \/>\n   __napi_poll<br \/>\n   net_rx_action<\/p>\n<p>  Freed by task 23:<br \/>\n   kfree<br \/>\n   pskb_expand_head<br \/>\n   __pskb_pull_tail<br \/>\n   mpls_select_multipath<\/p>\n<p>Reload hdr from the current skb head after each successful pull before<br \/>\nderiving the inner IPv4 or IPv6 header pointer.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In the Linux kernel, the following vulnerability has been resolved:<\/p>\n<p>mpls: reload header after pskb_may_pull()<\/p>\n<p>mpls_select_multipath() calls mpls_multipath_hash() to choose a nexthop<br \/>\nwhen an MPLS rou<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-21477","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/21477","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=21477"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=21477"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=21477"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}