# CVE-2026-31703: linux: In the Linux kernel, the following vulnerability has been resolved: writeback: Fix use after free in inode_switch_wb... CVE-2026-31703 is fixed in 34 products on 1 platform, first by ALAS2023-2026-1693, released May 8, 2026. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2026-31703 - Priority: High - CVSS: 7.8 (high) - EPSS: 0.0012 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: May 1, 2026 ## Description In the Linux kernel, the following vulnerability has been resolved: writeback: Fix use after free in inode_switch_wbs_work_fn() inode_switch_wbs_work_fn() has a loop like: wb_get(new_wb); while (1) { list = llist_del_all(&new_wb->switch_wbs_ctxs); /* Nothing to do? */ if (!list) break; ... process the items ... } Now adding of items to the list looks like: wb_queue_isw() if (llist_add(&isw->list, &wb->switch_wbs_ctxs)) queue_work(isw_wq, &wb->switch_work); Because inode_switch_wbs_work_fn() loops when processing isw items, it can happen that wb->switch_work is pending while wb->switch_wbs_ctxs is empty. This is a problem because in that case wb can get freed (no isw items -> no wb reference) while the work is still pending causing use-after-free issues. We cannot just fix this by cancelling work when freeing wb because that could still trigger problematic 0 -> 1 transitions on wb refcount due to wb_get() in inode_switch_wbs_work_fn(). It could be all handled with more careful code but that seems unnecessarily complex so let's avoid that until it is proven that the looping actually brings practical benefit. Just remove the loop from inode_switch_wbs_work_fn() instead. That way when wb_queue_isw() queues work, we are guaranteed we have added the first item to wb->switch_wbs_ctxs and nobody is going to remove it (and drop the wb reference it holds) until the queued work runs. ## 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 | dtb-aarch64 opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-64kb opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-64kb sles 15.7 | 6.4.0-150700.53.60.1 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-64kb sles 16.0 | 6.12.0-160000.35.1 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 2026 | | Linux | kernel-azure opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-azure sles 15.7 | 6.4.0-150700.53.60.1 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-azure sles 16.0 | 6.12.0-160000.35.1 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 2026 | | Linux | kernel-default opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-default sles 15.7 | 6.4.0-150700.53.60.1 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-default sles 16.0 | 6.12.0-160000.35.1 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 2026 | | Linux | kernel-default-base opensuse-leap 16.0 | 6.12.0-160000.35.1.160000.2.16 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-default-base sles 15.7 | 6.4.0-150700.53.60.1.150700.17.35.4 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-default-base sles 16.0 | 6.12.0-160000.35.1.160000.2.16 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 2026 | | Linux | kernel-docs opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-docs sles 15.7 | 6.4.0-150700.53.60.1 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-docs sles 16.0 | 6.12.0-160000.35.1 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 2026 | | Linux | kernel-kvmsmall opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-kvmsmall sles 16.0 | 6.12.0-160000.35.1 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 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 | kernel-livepatch-SLE15-SP7-RT_Update_16 sles 15.7 | 1-150700.1.5.2 | [SUSE-SU-2026:2591-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2591-1.md) | Jun 23, 2026 | | Linux | kernel-livepatch-SLE15-SP7_Update_16 sles 15.7 | 1-150700.15.3.2 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-obs-build opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-obs-build sles 15.7 | 6.4.0-150700.53.60.2 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-obs-qa opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-obs-qa sles 16.0 | 6.12.0-160000.35.1 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 2026 | | Linux | kernel-rt opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-source opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-source sles 15.7 | 6.4.0-150700.53.60.1 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-source sles 16.0 | 6.12.0-160000.35.1 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 2026 | | Linux | kernel-syms opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-syms sles 15.7 | 6.4.0-150700.53.60.1 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-syms sles 16.0 | 6.12.0-160000.35.1 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 2026 | | Linux | kernel-zfcpdump opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-zfcpdump sles 15.7 | 6.4.0-150700.53.60.1 | [SUSE-SU-2026:2482-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2482-1.md) | Jun 22, 2026 | | Linux | kernel-zfcpdump sles 16.0 | 6.12.0-160000.35.1 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 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 | 7.0.3-1 | [DEBIAN-CVE-2026-31703](https://patchblox.com/security/data/fix/linux/debian-cve-2026-31703.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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