# CVE-2026-31691: linux: In the Linux kernel, the following vulnerability has been resolved: igb: remove napi_synchronize() in igb_down() Wh... CVE-2026-31691 is fixed in 19 products on 1 platform, first by ALAS2023-2026-1693, released May 8, 2026. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2026-31691 - Priority: Routine - CVSS: 5.5 (medium) - EPSS: 0.0011 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Apr 27, 2026 ## Description In the Linux kernel, the following vulnerability has been resolved: igb: remove napi_synchronize() in igb_down() When an AF_XDP zero-copy application terminates abruptly (e.g., kill -9), the XSK buffer pool is destroyed but NAPI polling continues. igb_clean_rx_irq_zc() repeatedly returns the full budget, preventing napi_complete_done() from clearing NAPI_STATE_SCHED. igb_down() calls napi_synchronize() before napi_disable() for each queue vector. napi_synchronize() spins waiting for NAPI_STATE_SCHED to clear, which never happens. igb_down() blocks indefinitely, the TX watchdog fires, and the TX queue remains permanently stalled. napi_disable() already handles this correctly: it sets NAPI_STATE_DISABLE. After a full-budget poll, __napi_poll() checks napi_disable_pending(). If set, it forces completion and clears NAPI_STATE_SCHED, breaking the loop that napi_synchronize() cannot. napi_synchronize() was added in commit 41f149a285da ("igb: Fix possible panic caused by Rx traffic arrival while interface is down"). napi_disable() provides stronger guarantees: it prevents further scheduling and waits for any active poll to exit. Other Intel drivers (ixgbe, ice, i40e) use napi_disable() without a preceding napi_synchronize() in their down paths. Remove redundant napi_synchronize() call and reorder napi_disable() before igb_set_queue_napi() so the queue-to-NAPI mapping is only cleared after polling has fully stopped. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | bpftool6.18 amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | bpftool6.18-debuginfo amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel-livepatch-6.18.25-55.108 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18 amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-debuginfo amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-debuginfo-common-aarch64 amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-debuginfo-common-x86_64 amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-devel amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-headers amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-modules-extra amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-modules-extra-common amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-tools amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-tools-debuginfo amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-tools-devel amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | linux Debian 14 | 6.19.13-1 | [DEBIAN-CVE-2026-31691](https://patchblox.com/security/data/fix/linux/debian-cve-2026-31691.md) | May 15, 2026 | | Linux | perf6.18 amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | perf6.18-debuginfo amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | python3-perf6.18 amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | python3-perf6.18-debuginfo amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | --- Data as of 2026-11-09T01:18:40Z UTC. 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