How severe is CVE-2026-31609?

CVE-2026-31609 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-31609 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (50th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-31609?

CVE-2026-31609 affects Linux Linux Kernel. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-31609?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-31609 have an EU (EUVD) identifier?

Yes. CVE-2026-31609 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-25502.

When was CVE-2026-31609 published?

CVE-2026-31609 was published on 2026-04-24 and last updated on 2026-06-17.

CVE-2026-31609

CVE-2026-31609 is a critical-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-415.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 1% (50th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-25502
Weakness: CWE-415
Affected product: Linux Linux Kernel
Published: 2026-04-24
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-31609?: 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.
How severe is CVE-2026-31609?: CVE-2026-31609 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-31609 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (50th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-31609?: CVE-2026-31609 affects Linux Linux Kernel. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-31609?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-31609 have an EU (EUVD) identifier?: Yes. CVE-2026-31609 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-25502.
When was CVE-2026-31609 published?: CVE-2026-31609 was published on 2026-04-24 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

More vulnerabilities in Linux Linux Kernel

CVE-2026-63795 — Critical (CVSS 10.0): In the Linux kernel, the following vulnerability has been resolved: 9p: avoid putting oldfid in p9_client_walk() error…
CVE-2025-38429 — Critical (CVSS 10.0): In the Linux kernel, the following vulnerability has been resolved: bus: mhi: ep: Update read pointer only after…
CVE-2025-22021 — Critical (CVSS 10.0): In the Linux kernel, the following vulnerability has been resolved: netfilter: socket: Lookup orig tuple for IPv6…
CVE-2025-21663 — Critical (CVSS 10.0): In the Linux kernel, the following vulnerability has been resolved: net: stmmac: dwmac-tegra: Read iommu stream id…
CVE-2024-56719 — Critical (CVSS 10.0): In the Linux kernel, the following vulnerability has been resolved: net: stmmac: fix TSO DMA API usage causing…
CVE-2024-44984 — Critical (CVSS 10.0): In the Linux kernel, the following vulnerability has been resolved: bnxt_en: Fix double DMA unmapping for…

All CVEs affecting Linux Linux Kernel →

Other CWE-415 (Double Free) vulnerabilities

CVE-2018-0101 — Critical (CVSS 10.0): A vulnerability in the Secure Sockets Layer (SSL) VPN functionality of the Cisco Adaptive Security Appliance (ASA)…
CVE-2026-89078 — Critical (CVSS 9.9): GitLab has remediated an issue in GitLab CE/EE affecting all versions from 19.2 before 19.2.7, 19.3 before 19.3.3, and…
CVE-2026-84561 — Critical (CVSS 9.8): A double free issue was addressed with improved memory management. This issue is fixed in iOS 26.7 and iPadOS 26.7, iOS…
CVE-2026-77493 — Critical (CVSS 9.8): Double free in Microsoft Graphics Component allows an unauthorized attacker to execute code over a network.
CVE-2026-64387 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: smb: client: fix query directory replay…
CVE-2026-64386 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: smb: client: fix query_info() replay…

Browse all CWE-415 (Double Free) vulnerabilities →