{"cve":"CVE-2026-31691","nvd":{"published":"2026-04-27T18:16:54.610","modified":"2026-06-17T10:34:14.937","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nigb: remove napi_synchronize() in igb_down()\n\nWhen an AF_XDP zero-copy application terminates abruptly (e.g., kill -9),\nthe XSK buffer pool is destroyed but NAPI polling continues.\nigb_clean_rx_irq_zc() repeatedly returns the full budget, preventing\nnapi_complete_done() from clearing NAPI_STATE_SCHED.\n\nigb_down() calls napi_synchronize() before napi_disable() for each queue\nvector. napi_synchronize() spins waiting for NAPI_STATE_SCHED to clear,\nwhich never happens. igb_down() blocks indefinitely, the TX watchdog\nfires, and the TX queue remains permanently stalled.\n\nnapi_disable() already handles this correctly: it sets NAPI_STATE_DISABLE.\nAfter a full-budget poll, __napi_poll() checks napi_disable_pending(). If\nset, it forces completion and clears NAPI_STATE_SCHED, breaking the loop\nthat napi_synchronize() cannot.\n\nnapi_synchronize() was added in commit 41f149a285da (\"igb: Fix possible\npanic caused by Rx traffic arrival while interface is down\").\nnapi_disable() provides stronger guarantees: it prevents further\nscheduling and waits for any active poll to exit.\nOther Intel drivers (ixgbe, ice, i40e) use napi_disable() without a\npreceding napi_synchronize() in their down paths.\n\nRemove redundant napi_synchronize() call and reorder napi_disable()\nbefore igb_set_queue_napi() so the queue-to-NAPI mapping is only\ncleared after polling has fully stopped.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/27f5997686ee7fb7ac01be72b2010f168a3409fc","https://git.kernel.org/stable/c/4700471775746058c962ded6e659bf908fd76e13","https://git.kernel.org/stable/c/b1e067240379f950a0022208e0685f3465c211cb"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:33:09.003606135+00:00"},"epss":{"cve":"CVE-2026-31691","score":0.00112,"percentile":0.0138,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}