# CVE-2026-31609: smb: client: avoid double-free in smbd_free_send_io() after smbd_send_batch_flush()

CVE-2026-31609 is fixed in 19 products on 1 platform, first by DEBIAN-CVE-2026-31609, released May 15, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-31609
- Priority: High
- CVSS: 9.8 (Important)
- EPSS: 0.0046
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Apr 24, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-31609

## Description

In the Linux kernel, the following vulnerability has been resolved:  smb: client: avoid double-free in smbd_free_send_io() after smbd_send_batch_flush()  smbd_send_batch_flush() already calls smbd_free_send_io(), so we should not call it again after smbd_post_send() moved it to the batch list.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | bpftool6.18 amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 |
| Linux | bpftool6.18-debuginfo amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 |
| Linux | kernel-livepatch-6.18.25-52.107 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 |
| Linux | kernel6.18 amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 |
| Linux | kernel6.18-debuginfo amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 |
| Linux | kernel6.18-debuginfo-common-aarch64 amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 |
| Linux | kernel6.18-debuginfo-common-x86_64 amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 |
| Linux | kernel6.18-devel amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 |
| Linux | kernel6.18-headers amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 |
| Linux | kernel6.18-modules-extra amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 |
| Linux | kernel6.18-modules-extra-common amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 |
| Linux | kernel6.18-tools amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 |
| Linux | kernel6.18-tools-debuginfo amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 |
| Linux | kernel6.18-tools-devel amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 |
| Linux | linux Debian 14 | 6.19.14-1 | [DEBIAN-CVE-2026-31609](https://patchblox.com/security/data/fix/linux/debian-cve-2026-31609.md) | May 15, 2026 |
| Linux | perf6.18 amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 |
| Linux | perf6.18-debuginfo amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 |
| Linux | python3-perf6.18 amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 2026 |
| Linux | python3-perf6.18-debuginfo amzn 2023 | 1:6.18.25-52.107.amzn2023 | [ALAS2023-2026-1746](https://patchblox.com/security/data/fix/linux/alas2023-2026-1746.md) | May 25, 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.