{"id":"CVE-2026-99078","published":"2026-10-23T13:17:31.910","lastModified":"2026-10-24T14:16:54.790","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/mlx5e: Prevent stale XSK buffer release on MPWQE refill retry\n\nWith AF_XDP on a striding RQ, mlx5e defers releasing XSK buffers until\nan MPWQE is refilled. If XSK allocation then returns -ENOMEM,\nactual_wq_head is not advanced and a later NAPI poll retries the same\nWQE.\n\nmlx5e_free_rx_mpwqe() leaves each released slot marked as releasable. On\nretry it can therefore call xsk_buff_free() again through stale pointers\nafter the frames have returned to the XSK pool and been reallocated.\n\nSet all skip_release_bitmap bits in the common error path of\nmlx5e_xsk_alloc_rx_mpwqe(). This matches mlx5e_alloc_rx_mpwqe(). A\nsuccessful allocation already clears the bitmap after replacing every\nbuffer, so retries become idempotent without changing the success path.\n\nFault injection forced three consecutive failures for one selected MPWQE.\nBoth an early allocation failure and a partial 8-of-16-buffer unwind\nreleased the original 16 XSK buffers only once. Each error left a full\nbitmap, the following NAPI retry skipped the release, and a later\nsuccessful allocation cleared it. A 20-second AF_XDP zero-copy pressure\nrun exercised 1,575,262 buffer allocation failures without invalid\ndescriptors, WQE errors, or kernel warnings.","cvssScore":9.8,"cvssSeverity":"CRITICAL","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/3d73a1164a8c6b4461907a65cb6c022ea4fd39af","tags":[]},{"url":"https://git.kernel.org/stable/c/63811edf512584c946e5e96b100e9e280703bbb5","tags":[]},{"url":"https://git.kernel.org/stable/c/867119b4b588037724b85839d534465f0334d9bd","tags":[]},{"url":"https://git.kernel.org/stable/c/d215d09606b0fcd18ad1eb532995782a21cea49d","tags":[]},{"url":"https://git.kernel.org/stable/c/f3a52e2ec2788a7f6b64137985c087188a54ad4f","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":{"summary":"A flaw in the Linux kernel's mlx5e driver allows reuse of freed XSK buffers on striding RQ when MPWQE refill fails and retries occur, potentially leading to use-after-free or double-free of XSK buffer frames.","exploitability":"Exploitation requires an attacker-controlled workload using AF_XDP with striding RQ that triggers repeated XSK allocation failures (-ENOMEM) to force retry of the same WQE and reuse of stale buffer pointers.","blast_radius":"Successful exploitation could allow an unprivileged user with access to AF_XDP to corrupt kernel memory, potentially leading to privilege escalation or system crash.","remediation":"Apply the fix described in the patch: ensure skip_release_bitmap is fully set in the common error path of mlx5e_xsk_alloc_rx_mpwqe() to prevent double-free on retry; no fixed kernel version is specified in the description, so apply the referenced patch or upgrade to a kernel version that includes commit 1a2b3c4d (hypothetical placeholder — use actual commit ID or vendor advisory if available).","detection":"No reliable host or network indicator is derivable from the published description.","tags":["use-after-free","double-free","af-xdp","kernel","memory-corruption"],"model":"garnet-coder","analyzedAt":"2026-10-25T08:44:16.776Z"}}