# CVE-2026-46139: linux: In the Linux kernel, the following vulnerability has been resolved: smb: client: use kzalloc to zero-initialize secu... CVE-2026-46139 is fixed in 37 products on 1 platform, first by ALAS2023-2026-1753, released May 25, 2026. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2026-46139 - Priority: Routine - CVSS: 5.5 (medium) - EPSS: 0.0012 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: May 25, 2026 ## Description In the Linux kernel, the following vulnerability has been resolved: smb: client: use kzalloc to zero-initialize security descriptor buffer Commit 62e7dd0a39c2d ("smb: common: change the data type of num_aces to le16") split struct smb_acl's __le32 num_aces field into __le16 num_aces and __le16 reserved. The reserved field corresponds to Sbz2 in the MS-DTYP ACL wire format, which must be zero [1]. When building an ACL descriptor in build_sec_desc(), we are using a kmalloc()'ed descriptor buffer and writing the fields explicitly using le16() writes now. This never writes to the 2 byte reserved field, leaving it as uninitialized heap data. When the reserved field happens to contain non-zero slab garbage, Samba rejects the security descriptor with "ndr_pull_security_descriptor failed: Range Error", causing chmod to fail with EINVAL. Change kmalloc() to kzalloc() to ensure the entire buffer is zero-initialized. [1] https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-dtyp/20233ed8-a6c6-4097-aafa-dd545ed24428 ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | bpftool6.12 amzn 2023 | 1:6.12.88-119.157.amzn2023 | [ALAS2023-2026-1753](https://patchblox.com/security/data/fix/linux/alas2023-2026-1753.md) | May 25, 2026 | | Linux | bpftool6.12-debuginfo amzn 2023 | 1:6.12.88-119.157.amzn2023 | [ALAS2023-2026-1753](https://patchblox.com/security/data/fix/linux/alas2023-2026-1753.md) | May 25, 2026 | | Linux | bpftool6.18 amzn 2023 | 1:6.18.30-61.116.amzn2023 | [ALAS2023-2026-1754](https://patchblox.com/security/data/fix/linux/alas2023-2026-1754.md) | May 25, 2026 | | Linux | bpftool6.18-debuginfo amzn 2023 | 1:6.18.30-61.116.amzn2023 | [ALAS2023-2026-1754](https://patchblox.com/security/data/fix/linux/alas2023-2026-1754.md) | May 25, 2026 | | Linux | kernel-livepatch-6.12.88-119.157 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-1753](https://patchblox.com/security/data/fix/linux/alas2023-2026-1753.md) | May 25, 2026 | | Linux | kernel-livepatch-6.18.30-61.116 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-1754](https://patchblox.com/security/data/fix/linux/alas2023-2026-1754.md) | May 25, 2026 | | Linux | kernel6.12 amzn 2023 | 1:6.12.88-119.157.amzn2023 | [ALAS2023-2026-1753](https://patchblox.com/security/data/fix/linux/alas2023-2026-1753.md) | May 25, 2026 | | Linux | kernel6.12-debuginfo amzn 2023 | 1:6.12.88-119.157.amzn2023 | [ALAS2023-2026-1753](https://patchblox.com/security/data/fix/linux/alas2023-2026-1753.md) | May 25, 2026 | | Linux | kernel6.12-debuginfo-common-aarch64 amzn 2023 | 1:6.12.88-119.157.amzn2023 | [ALAS2023-2026-1753](https://patchblox.com/security/data/fix/linux/alas2023-2026-1753.md) | May 25, 2026 | | Linux | kernel6.12-debuginfo-common-x86_64 amzn 2023 | 1:6.12.88-119.157.amzn2023 | [ALAS2023-2026-1753](https://patchblox.com/security/data/fix/linux/alas2023-2026-1753.md) | May 25, 2026 | | Linux | kernel6.12-devel amzn 2023 | 1:6.12.88-119.157.amzn2023 | [ALAS2023-2026-1753](https://patchblox.com/security/data/fix/linux/alas2023-2026-1753.md) | May 25, 2026 | | Linux | kernel6.12-headers amzn 2023 | 1:6.12.88-119.157.amzn2023 | [ALAS2023-2026-1753](https://patchblox.com/security/data/fix/linux/alas2023-2026-1753.md) | May 25, 2026 | | Linux | kernel6.12-modules-extra amzn 2023 | 1:6.12.88-119.157.amzn2023 | [ALAS2023-2026-1753](https://patchblox.com/security/data/fix/linux/alas2023-2026-1753.md) | May 25, 2026 | | Linux | kernel6.12-modules-extra-common amzn 2023 | 1:6.12.88-119.157.amzn2023 | [ALAS2023-2026-1753](https://patchblox.com/security/data/fix/linux/alas2023-2026-1753.md) | May 25, 2026 | | Linux | kernel6.12-tools amzn 2023 | 1:6.12.88-119.157.amzn2023 | [ALAS2023-2026-1753](https://patchblox.com/security/data/fix/linux/alas2023-2026-1753.md) | May 25, 2026 | | Linux | kernel6.12-tools-debuginfo amzn 2023 | 1:6.12.88-119.157.amzn2023 | [ALAS2023-2026-1753](https://patchblox.com/security/data/fix/linux/alas2023-2026-1753.md) | May 25, 2026 | | Linux | kernel6.12-tools-devel amzn 2023 | 1:6.12.88-119.157.amzn2023 | [ALAS2023-2026-1753](https://patchblox.com/security/data/fix/linux/alas2023-2026-1753.md) | May 25, 2026 | | Linux | kernel6.18 amzn 2023 | 1:6.18.30-61.116.amzn2023 | [ALAS2023-2026-1754](https://patchblox.com/security/data/fix/linux/alas2023-2026-1754.md) | May 25, 2026 | | Linux | kernel6.18-debuginfo amzn 2023 | 1:6.18.30-61.116.amzn2023 | [ALAS2023-2026-1754](https://patchblox.com/security/data/fix/linux/alas2023-2026-1754.md) | May 25, 2026 | | Linux | kernel6.18-debuginfo-common-aarch64 amzn 2023 | 1:6.18.30-61.116.amzn2023 | [ALAS2023-2026-1754](https://patchblox.com/security/data/fix/linux/alas2023-2026-1754.md) | May 25, 2026 | | Linux | kernel6.18-debuginfo-common-x86_64 amzn 2023 | 1:6.18.30-61.116.amzn2023 | [ALAS2023-2026-1754](https://patchblox.com/security/data/fix/linux/alas2023-2026-1754.md) | May 25, 2026 | | Linux | kernel6.18-devel amzn 2023 | 1:6.18.30-61.116.amzn2023 | [ALAS2023-2026-1754](https://patchblox.com/security/data/fix/linux/alas2023-2026-1754.md) | May 25, 2026 | | Linux | kernel6.18-headers amzn 2023 | 1:6.18.30-61.116.amzn2023 | [ALAS2023-2026-1754](https://patchblox.com/security/data/fix/linux/alas2023-2026-1754.md) | May 25, 2026 | | Linux | kernel6.18-modules-extra amzn 2023 | 1:6.18.30-61.116.amzn2023 | [ALAS2023-2026-1754](https://patchblox.com/security/data/fix/linux/alas2023-2026-1754.md) | May 25, 2026 | | Linux | kernel6.18-modules-extra-common amzn 2023 | 1:6.18.30-61.116.amzn2023 | [ALAS2023-2026-1754](https://patchblox.com/security/data/fix/linux/alas2023-2026-1754.md) | May 25, 2026 | | Linux | kernel6.18-tools amzn 2023 | 1:6.18.30-61.116.amzn2023 | [ALAS2023-2026-1754](https://patchblox.com/security/data/fix/linux/alas2023-2026-1754.md) | May 25, 2026 | | Linux | kernel6.18-tools-debuginfo amzn 2023 | 1:6.18.30-61.116.amzn2023 | [ALAS2023-2026-1754](https://patchblox.com/security/data/fix/linux/alas2023-2026-1754.md) | May 25, 2026 | | Linux | kernel6.18-tools-devel amzn 2023 | 1:6.18.30-61.116.amzn2023 | [ALAS2023-2026-1754](https://patchblox.com/security/data/fix/linux/alas2023-2026-1754.md) | May 25, 2026 | | Linux | linux Debian 13.5 (trixie) | 6.12.88-1 | [DEBIAN-CVE-2026-46139](https://patchblox.com/security/data/fix/linux/debian-cve-2026-46139.md) | Jun 24, 2026 | | Linux | linux Debian 14 | 7.0.7-1 | [DEBIAN-CVE-2026-46139](https://patchblox.com/security/data/fix/linux/debian-cve-2026-46139.md) | Jun 24, 2026 | | Linux | perf6.12 amzn 2023 | 1:6.12.88-119.157.amzn2023 | [ALAS2023-2026-1753](https://patchblox.com/security/data/fix/linux/alas2023-2026-1753.md) | May 25, 2026 | | Linux | perf6.12-debuginfo amzn 2023 | 1:6.12.88-119.157.amzn2023 | [ALAS2023-2026-1753](https://patchblox.com/security/data/fix/linux/alas2023-2026-1753.md) | May 25, 2026 | | Linux | perf6.18 amzn 2023 | 1:6.18.30-61.116.amzn2023 | [ALAS2023-2026-1754](https://patchblox.com/security/data/fix/linux/alas2023-2026-1754.md) | May 25, 2026 | | Linux | perf6.18-debuginfo amzn 2023 | 1:6.18.30-61.116.amzn2023 | [ALAS2023-2026-1754](https://patchblox.com/security/data/fix/linux/alas2023-2026-1754.md) | May 25, 2026 | | Linux | python3-perf6.12 amzn 2023 | 1:6.12.88-119.157.amzn2023 | [ALAS2023-2026-1753](https://patchblox.com/security/data/fix/linux/alas2023-2026-1753.md) | May 25, 2026 | | Linux | python3-perf6.12-debuginfo amzn 2023 | 1:6.12.88-119.157.amzn2023 | [ALAS2023-2026-1753](https://patchblox.com/security/data/fix/linux/alas2023-2026-1753.md) | May 25, 2026 | | Linux | python3-perf6.18 amzn 2023 | 1:6.18.30-61.116.amzn2023 | [ALAS2023-2026-1754](https://patchblox.com/security/data/fix/linux/alas2023-2026-1754.md) | May 25, 2026 | | Linux | python3-perf6.18-debuginfo amzn 2023 | 1:6.18.30-61.116.amzn2023 | [ALAS2023-2026-1754](https://patchblox.com/security/data/fix/linux/alas2023-2026-1754.md) | May 25, 2026 | --- Data as of 2026-11-09T01:18:40Z UTC. 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