# CVE-2026-23436: linux: In the Linux kernel, the following vulnerability has been resolved: net: shaper: protect from late creation of hiera... CVE-2026-23436 is fixed in 23 products on 1 platform, first by DEBIAN-CVE-2026-23436, released April 3, 2026. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2026-23436 - Priority: Routine - CVSS: 5.5 (medium) - EPSS: 0.0013 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Apr 3, 2026 ## Description In the Linux kernel, the following vulnerability has been resolved: net: shaper: protect from late creation of hierarchy We look up a netdev during prep of Netlink ops (pre- callbacks) and take a ref to it. Then later in the body of the callback we take its lock or RCU which are the actual protections. The netdev may get unregistered in between the time we take the ref and the time we lock it. We may allocate the hierarchy after flush has already run, which would lead to a leak. Take the instance lock in pre- already, this saves us from the race and removes the need for dedicated lock/unlock callbacks completely. After all, if there's any chance of write happening concurrently with the flush - we're back to leaking the hierarchy. We may take the lock for devices which don't support shapers but we're only dealing with SET operations here, not taking the lock would be optimizing for an error case. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | bpftool6.18 amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | bpftool6.18-debuginfo amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | kernel-livepatch-6.18.20-20.229 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | kernel6.18 amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | kernel6.18-debuginfo amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | kernel6.18-debuginfo-common-aarch64 amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | kernel6.18-debuginfo-common-x86_64 amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | kernel6.18-devel amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | kernel6.18-headers amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | kernel6.18-libbpf amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | kernel6.18-libbpf-debuginfo amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | kernel6.18-libbpf-devel amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | kernel6.18-libbpf-static amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | kernel6.18-modules-extra amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | kernel6.18-modules-extra-common amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | kernel6.18-tools amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | kernel6.18-tools-debuginfo amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | kernel6.18-tools-devel amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | linux Debian 14 | 6.19.10-1 | [DEBIAN-CVE-2026-23436](https://patchblox.com/security/data/fix/linux/debian-cve-2026-23436.md) | Apr 3, 2026 | | Linux | perf6.18 amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | perf6.18-debuginfo amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | python3-perf6.18 amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | | Linux | python3-perf6.18-debuginfo amzn 2023 | 1:6.18.20-20.229.amzn2023 | [ALAS2023-2026-1596](https://patchblox.com/security/data/fix/linux/alas2023-2026-1596.md) | Apr 27, 2026 | --- Data as of 2026-11-09T07:25:28Z UTC. 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