# CVE-2026-93275: perf/x86/intel/pt: Fix stop/start with no update CVE-2026-93275 is fixed in 38 products on 1 platform, first by DEBIAN-CVE-2026-93275, released September 24, 2026. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2026-93275 - Priority: Routine - CVSS: 2.5 (Low) - EPSS: 0.0019 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Sep 24, 2026 - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-93275 ## Description In the Linux kernel, the following vulnerability has been resolved: perf/x86/intel/pt: Fix stop/start with no update If pt_event_stop() is called without PERF_EF_UPDATE flag, then perf_aux_output_end() is not called. A subsequent call to pt_event_start() will call perf_aux_output_begin() again which violates the rule against nesting and triggers a WARNING in perf_aux_output_begin(). Originally, pt_event_stop() was never called without PERF_EF_UPDATE, because the only code paths to do so are from event overflow, and Intel PT does not do that. However the introduction of group throttling by commit 9734e25fbf5ae ("perf: Fix the throttle logic for a group") meant that an Intel PT event could be throttled if it was part of a group. Throttling calls PMU ->stop() / ->start() callbacks without flags. An example is when AUX area sampling is used. The following commands hit the issue: echo 10000 > /proc/sys/kernel/perf_event_max_sample_rate perf record -F32000 --aux-sample -e '{intel_pt//u,cycles:u}' \ -- bash -c 'for i in `seq 1 100000` ; do true ; done' Use PERF_HES_UPTODATE to track whether perf_aux_output_begin() and perf_aux_output_end() are balanced. A cleared PERF_HES_UPTODATE bit indicates that an AUX output context is still open. Amend pt_event_start() / pt_event_stop() accordingly so that begin/end stay balanced: - In non-snapshot mode, stop() always closes the buffer (the buffer may have run out of space, and that accounting is done by the update), so a following start() opens a fresh one as before. - In snapshot/overwrite mode, stop() without PERF_EF_UPDATE leaves the buffer open so that pt_event_snapshot_aux() can still copy from it, and start() then only re-enables tracing instead of calling perf_aux_output_begin() again. Note that pt_event_del() calls pt_event_stop() with PERF_EF_UPDATE flag set (as is required by the documentation), so a final call to perf_aux_output_end() is assured. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | bpftool6.12 amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 | | Linux | bpftool6.12-debuginfo amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 | | Linux | bpftool6.18 amzn 2023 | 1:6.18.54-121.166.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | | Linux | bpftool6.18-debuginfo amzn 2023 | 1:6.18.54-121.166.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | | Linux | kernel-livepatch-6.12.110-135.201 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 | | Linux | kernel-livepatch-6.18.54-121.166 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | | Linux | kernel6.12 amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 | | Linux | kernel6.12-debuginfo amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 | | Linux | kernel6.12-debuginfo-common-aarch64 amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 | | Linux | kernel6.12-debuginfo-common-x86_64 amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 | | Linux | kernel6.12-devel amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 | | Linux | kernel6.12-headers amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 | | Linux | kernel6.12-modules-extra amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 | | Linux | kernel6.12-modules-extra-common amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 | | Linux | kernel6.12-tools amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 | | Linux | kernel6.12-tools-debuginfo amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 | | Linux | kernel6.12-tools-devel amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 | | Linux | kernel6.18 amzn 2023 | 1:6.18.54-121.166.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | | Linux | kernel6.18-debuginfo amzn 2023 | 1:6.18.54-121.166.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | | Linux | kernel6.18-debuginfo-common-aarch64 amzn 2023 | 1:6.18.54-121.166.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | | Linux | kernel6.18-debuginfo-common-x86_64 amzn 2023 | 1:6.18.54-121.166.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | | Linux | kernel6.18-devel amzn 2023 | 1:6.18.54-121.166.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | | Linux | kernel6.18-headers amzn 2023 | 1:6.18.54-121.166.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | | Linux | kernel6.18-modules-extra amzn 2023 | 1:6.18.54-121.166.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | | Linux | kernel6.18-modules-extra-common amzn 2023 | 1:6.18.54-121.166.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | | Linux | kernel6.18-tools amzn 2023 | 1:6.18.54-121.166.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | | Linux | kernel6.18-tools-debuginfo amzn 2023 | 1:6.18.54-121.166.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | | Linux | kernel6.18-tools-devel amzn 2023 | 1:6.18.54-121.166.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | | Linux | linux Debian 14 | 7.2.6-1 | [DEBIAN-CVE-2026-93275](https://patchblox.com/security/data/fix/linux/debian-cve-2026-93275.md) | Sep 24, 2026 | | Linux | microvm-kernel6.18 amzn 2023 | 1:6.18.54-121.166.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | | Linux | perf6.12 amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 | | Linux | perf6.12-debuginfo amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 | | Linux | perf6.18 amzn 2023 | 1:6.18.54-121.166.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | | Linux | perf6.18-debuginfo amzn 2023 | 1:6.18.54-121.166.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | | Linux | python3-perf6.12 amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 | | Linux | python3-perf6.12-debuginfo amzn 2023 | 1:6.12.110-135.201.amzn2023 | [ALAS2023-2026-3196](https://patchblox.com/security/data/fix/linux/alas2023-2026-3196.md) | Nov 7, 2026 | | Linux | python3-perf6.18 amzn 2023 | 1:6.18.54-121.166.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | | Linux | python3-perf6.18-debuginfo amzn 2023 | 1:6.18.54-121.166.amzn2023 | [ALAS2023-2026-3192](https://patchblox.com/security/data/fix/linux/alas2023-2026-3192.md) | Nov 7, 2026 | --- Data as of 2026-11-09T07:25:28Z UTC. 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