VulnerabilityPublished 19 Jul 2026

CVE-2026-63929: Linux kernel · iio: buffer: Fix DMA fence leak in iio_buffer_enqueue_dmabuf()

Affects Linux kernelSource GCVE Database

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Not known to be exploited.

Data as of 30 Oct 2026, 15:48 UTC

Severity

Medium

Rated Medium by Threat Radar's AI analysis · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Exploitation evidence

Disclosed: evidence found.
CVE published 19 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

AI-suggested

A fix is available that properly releases the DMA fence reference to prevent the memory leak. Users should apply the official Linux kernel patch that includes this fix. Since this is a kernel vulnerability, updating to a fixed kernel version or applying the patch from the vendor is the recommended mitigation.

Description

A memory leak vulnerability in the Linux kernel's Industrial I/O (iio) buffer subsystem was fixed. The function iio_buffer_enqueue_dmabuf() failed to release an initial reference to a DMA fence object, causing a permanent memory leak of 128-byte allocations. This leak accumulates rapidly under typical usage, leading to increased kernel memory consumption. The issue was resolved by properly releasing the DMA fence reference after it is added to the DMA reservation object.

Impact

The vulnerability causes a memory leak in the kernel, which can lead to increased memory consumption and potential resource exhaustion over time. This could degrade system performance or stability, especially under workloads involving multiple iio_rwdev instances with high-frequency buffer enqueues. There is no indication of direct code execution or privilege escalation from this issue.

Summary

CVE-2026-63929 addresses a memory leak in the Linux kernel's iio_buffer_enqueue_dmabuf() function. The function allocates a struct iio_dma_fence with an initial reference count of 1, then adds a second reference via dma_resv_add_fence(). However, it fails to release the initial reference, resulting in a permanent leak of kmalloc-128 allocations. This leak manifests as continuous growth in kernel memory usage during buffer enqueue operations. The fix involves calling dma_fence_put() after dma_resv_add_fence() to transfer ownership and ensure proper cleanup of the DMA fence after signaling.

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 30 Oct 2026, 15:48 UTC

Technical details

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