# CVE-2026-43455: linux: In the Linux kernel, the following vulnerability has been resolved: mctp: route: hold key->lock in mctp_flow_prepare... CVE-2026-43455 is fixed in 16 products on 1 platform, first by DEBIAN-CVE-2026-43455, released May 15, 2026. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2026-43455 - Priority: Routine - CVSS: 5.5 (medium) - EPSS: 0.0011 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: May 8, 2026 ## Description In the Linux kernel, the following vulnerability has been resolved: mctp: route: hold key->lock in mctp_flow_prepare_output() mctp_flow_prepare_output() checks key->dev and may call mctp_dev_set_key(), but it does not hold key->lock while doing so. mctp_dev_set_key() and mctp_dev_release_key() are annotated with __must_hold(&key->lock), so key->dev access is intended to be serialized by key->lock. The mctp_sendmsg() transmit path reaches mctp_flow_prepare_output() via mctp_local_output() -> mctp_dst_output() without holding key->lock, so the check-and-set sequence is racy. Example interleaving: CPU0 CPU1 ---- ---- mctp_flow_prepare_output(key, devA) if (!key->dev) // sees NULL mctp_flow_prepare_output( key, devB) if (!key->dev) // still NULL mctp_dev_set_key(devB, key) mctp_dev_hold(devB) key->dev = devB mctp_dev_set_key(devA, key) mctp_dev_hold(devA) key->dev = devA // overwrites devB Now both devA and devB references were acquired, but only the final key->dev value is tracked for release. One reference can be lost, causing a resource leak as mctp_dev_release_key() would only decrease the reference on one dev. Fix by taking key->lock around the key->dev check and mctp_dev_set_key() call. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | 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-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 | linux Debian 12.15 (bookworm) | 6.1.170-1 | [DEBIAN-CVE-2026-43455](https://patchblox.com/security/data/fix/linux/debian-cve-2026-43455.md) | May 15, 2026 | | Linux | linux Debian 13.5 (trixie) | 6.12.85-1 | [DEBIAN-CVE-2026-43455](https://patchblox.com/security/data/fix/linux/debian-cve-2026-43455.md) | May 15, 2026 | | Linux | linux Debian 14 | 6.19.10-1 | [DEBIAN-CVE-2026-43455](https://patchblox.com/security/data/fix/linux/debian-cve-2026-43455.md) | May 15, 2026 | --- Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.