Threats Tagged 'cve-2026-43501'

In the Linux kernel, the following vulnerability has been resolved: ipv6: rpl: reserve mac_len headroom when recompressed SRH grows ipv6_rpl_srh_rcv() decompresses an RFC 6554 Source Routing Header, swaps the next segment into ipv6_hdr->daddr, recompresses, then pulls the old header and pushes the new one plus the IPv6 header back. The recompressed header can be larger than the received one when the swap reduces the common-prefix length the segments share with daddr (CmprI=0, CmprE>0, seg[0][0] != daddr[0] gives the maximum +8 bytes). pskb_expand_head() was gated on segments_left == 0, so on earlier segments the push consumed unchecked headroom. Once skb_push() leaves fewer than skb->mac_len bytes in front of data, skb_mac_header_rebuild()'s call to: skb_set_mac_header(skb, -skb->mac_len); will store (data - head) - mac_len into the u16 mac_header field, which wraps to ~65530, and the following memmove() writes mac_len bytes ~64KiB past skb->head. A single AF_INET6/SOCK_RAW/IPV6_HDRINCL packet over lo with a two segment type-3 SRH (CmprI=0, CmprE=15) reaches headroom 8 after one pass; KASAN reports a 14-byte OOB write in ipv6_rthdr_rcv. Fix this by expanding the head whenever the remaining room is less than the push size plus mac_len, and request that much extra so the rebuilt MAC header fits afterwards.

A critical vulnerability (CVE-2026-43501) in the Linux kernel's IPv6 implementation involving the recompression of the Source Routing Header (SRH) in the RPL protocol can lead to an out-of-bounds write. This occurs when the recompressed SRH grows larger than the original due to changes in segment address compression, causing a memory overwrite past the skb->head buffer. The flaw is triggered during packet processing and can result in memory corruption. Red Hat has issued a security advisory with a patch to fix this by expanding the headroom to accommodate the larger header. The vulnerability is rated critical due to its potential impact on confidentiality, integrity, and availability. Systems running affected kernel versions should apply the update and reboot to mitigate the issue.

This Red Hat security advisory addresses multiple vulnerabilities and bugs in the Linux kernel packages for Red Hat Enterprise Linux 9.6 Extended Update Support and related products. The update includes fixes for 18 CVEs affecting various kernel subsystems such as netfilter, ALSA, RDMA, TCP, SCTP, and others. The advisory rates the security impact as Important and covers issues like use-after-free, double free, race conditions, permission checking flaws, and validation errors. The update also includes bug fixes and enhancements unrelated to security. Systems must be rebooted after applying the update for changes to take effect.