{"id":"CVE-2026-99079","state":"PUBLISHED","title":"net/mlx5e: Prevent stale XSK buffer release on refill retry","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/mlx5e: Prevent stale XSK buffer release on refill retry\n\nWhen an XDP redirect to an AF_XDP socket fails because its RX ring is\nfull, the XSK core frees the buffer. During the subsequent batched refill\nof a legacy cyclic RQ, mlx5e also releases the WQE's XSK buffer before\nallocating a replacement. If that refill succeeds only partially, a WQE\nleft without a replacement retains its old buffer pointer.\n\nThe buffer can meanwhile be allocated to another WQE. A later refill\nretry can then free the live buffer through the stale pointer and publish\nthe same UMEM frame twice.\n\nMark the WQE as released immediately after the driver-side free. The flag\nis already cleared when a replacement buffer is assigned, so refill\nretries no longer release stale pointers.\n\nThe failure is silent and produces no kernel warning or splat. A\nstandalone legacy cyclic-RQ zero-copy libxsk reproducer, using 64-byte UDP\ntraffic offered at 12 Mpps, detected it: stock stopped after 2,854,914\npackets in 4.094 seconds, with 4,542 xdp_rx_ring_full events and 64\nownership/double-publication errors. With this change it processed\n356,904,225 packets in 30 seconds despite 571,405 xdp_rx_ring_full events,\nwith no ownership or data errors.","publishedAt":"2026-10-23T12:23:26.458Z","updatedAt":"2026-10-24T14:10:21.247Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"3f93f82988bc6b4104314bf9aa485d47fbb7e241","status":"affected","lessThan":"32bbb870078d467479965c21bbc4960c57eea208","versionType":"git"},{"version":"3f93f82988bc6b4104314bf9aa485d47fbb7e241","status":"affected","lessThan":"34d1db2b18e1c1d189e34dd51923e031815f88e3","versionType":"git"},{"version":"3f93f82988bc6b4104314bf9aa485d47fbb7e241","status":"affected","lessThan":"639522e5056cade578a324acfa993ec6c9f7f5dc","versionType":"git"},{"version":"3f93f82988bc6b4104314bf9aa485d47fbb7e241","status":"affected","lessThan":"655f47477054d19de3b138840be229a1a4490d0c","versionType":"git"},{"version":"3f93f82988bc6b4104314bf9aa485d47fbb7e241","status":"affected","lessThan":"e01620844c5c88b6fcf819d171df8e3976a0e76f","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/ethernet/mellanox/mlx5/core/en_rx.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.4","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.4","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.113","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.11","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/ethernet/mellanox/mlx5/core/en_rx.c"]}],"references":["https://git.kernel.org/stable/c/32bbb870078d467479965c21bbc4960c57eea208","https://git.kernel.org/stable/c/34d1db2b18e1c1d189e34dd51923e031815f88e3","https://git.kernel.org/stable/c/639522e5056cade578a324acfa993ec6c9f7f5dc","https://git.kernel.org/stable/c/655f47477054d19de3b138840be229a1a4490d0c","https://git.kernel.org/stable/c/e01620844c5c88b6fcf819d171df8e3976a0e76f"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/99xxx/CVE-2026-99079.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-99079","state":"PUBLISHED","datePublished":"2026-10-23T12:23:26.458Z","dateUpdated":"2026-10-24T14:10:21.247Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.389Z"},"containers":{"cna":{"title":"net/mlx5e: Prevent stale XSK buffer release on refill retry","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/mlx5e: Prevent stale XSK buffer release on refill retry\n\nWhen an XDP redirect to an AF_XDP socket fails because its RX ring is\nfull, the XSK core frees the buffer. During the subsequent batched refill\nof a legacy cyclic RQ, mlx5e also releases the WQE's XSK buffer before\nallocating a replacement. If that refill succeeds only partially, a WQE\nleft without a replacement retains its old buffer pointer.\n\nThe buffer can meanwhile be allocated to another WQE. A later refill\nretry can then free the live buffer through the stale pointer and publish\nthe same UMEM frame twice.\n\nMark the WQE as released immediately after the driver-side free. The flag\nis already cleared when a replacement buffer is assigned, so refill\nretries no longer release stale pointers.\n\nThe failure is silent and produces no kernel warning or splat. A\nstandalone legacy cyclic-RQ zero-copy libxsk reproducer, using 64-byte UDP\ntraffic offered at 12 Mpps, detected it: stock stopped after 2,854,914\npackets in 4.094 seconds, with 4,542 xdp_rx_ring_full events and 64\nownership/double-publication errors. With this change it processed\n356,904,225 packets in 30 seconds despite 571,405 xdp_rx_ring_full events,\nwith no ownership or data errors."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"3f93f82988bc6b4104314bf9aa485d47fbb7e241","status":"affected","lessThan":"32bbb870078d467479965c21bbc4960c57eea208","versionType":"git"},{"version":"3f93f82988bc6b4104314bf9aa485d47fbb7e241","status":"affected","lessThan":"34d1db2b18e1c1d189e34dd51923e031815f88e3","versionType":"git"},{"version":"3f93f82988bc6b4104314bf9aa485d47fbb7e241","status":"affected","lessThan":"639522e5056cade578a324acfa993ec6c9f7f5dc","versionType":"git"},{"version":"3f93f82988bc6b4104314bf9aa485d47fbb7e241","status":"affected","lessThan":"655f47477054d19de3b138840be229a1a4490d0c","versionType":"git"},{"version":"3f93f82988bc6b4104314bf9aa485d47fbb7e241","status":"affected","lessThan":"e01620844c5c88b6fcf819d171df8e3976a0e76f","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/ethernet/mellanox/mlx5/core/en_rx.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.4","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.4","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.113","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.11","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/ethernet/mellanox/mlx5/core/en_rx.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/32bbb870078d467479965c21bbc4960c57eea208"},{"url":"https://git.kernel.org/stable/c/34d1db2b18e1c1d189e34dd51923e031815f88e3"},{"url":"https://git.kernel.org/stable/c/639522e5056cade578a324acfa993ec6c9f7f5dc"},{"url":"https://git.kernel.org/stable/c/655f47477054d19de3b138840be229a1a4490d0c"},{"url":"https://git.kernel.org/stable/c/e01620844c5c88b6fcf819d171df8e3976a0e76f"}],"metrics":[{"cvssV3_1":{"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"},"scenarios":[{"lang":"en","value":"AV:N - UDP datagrams reaching mlx5 drive mlx5e_completion_event() -> mlx5e_napi_poll() -> mlx5e_poll_rx_cq()/XDP redirect, then mlx5e_napi_xsk_post() -> mlx5e_post_rx_wqes() -> patched mlx5e_xsk_free_rx_wqe(); sustained routable traffic fills the XSK RX ring and triggers stale release.\nAC:L - A sender can sustain small-packet traffic until __xsk_rcv_zc() reports RX-ring-full and mlx5e_xsk_alloc_rx_wqes_batched() refills only part of the missing WQEs; retries are deterministic and require no uncontrolled race or memory layout.\nPR:N - The NIC-CQE/NAPI receive path contains no capability or authentication check; xsk_create()'s CAP_NET_RAW check applies to victim-side AF_XDP provisioning, while the remote UDP sender needs no privileges.\nUI:N - Once the zero-copy XSK pool and XDP redirect are active, xsk_rcv_zc() failure, mlx5e_napi_xsk_post(), and refill retries occur automatically as packets arrive, without further victim action.\nS:U - mlx5e_xsk_free_rx_wqe() corrupts the host kernel's xsk_buff_pool and mlx5 receive state without crossing a VM, IOMMU, or other security-authority boundary.\nC:H - Duplicate xdp_buff_xsk ownership lets repeated successful __xsk_rcv_zc() calls invoke unbounded xp_release(); in unaligned-UMEM mode, free_heads_cnt can write kernel pointers past the flexible free_heads[] array, yielding heap corruption exploitable for arbitrary disclosure.\nI:H - The duplicate WQEs can make xp_release() write beyond free_heads[], while xp_get_xskb() later trusts pointers popped through the corrupted count; this supplies out-of-bounds and corrupted-pointer write primitives capable of control-flow hijacking.\nA:H - The free_heads[] overflow or a bogus xskb consumed by xp_get_xskb() can oops or panic; additionally, the dma_dev_need_sync refill path can store NULL on allocation failure and have the stale retry pass it to xsk_buff_free()."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-24T14:10:21.247Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.4","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.4","versionEndExcluding":"6.12.113"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.4","versionEndExcluding":"6.18.57"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.4","versionEndExcluding":"7.2.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.4","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}