VulnerabilityPublished 23 Oct 2026

CVE-2026-99039: Linux kernel · memstick: core: wait for request completion before freeing card

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in f2795c50144d528dabc2cf2fd53c0f0c63a823a1 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:30 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in f2795c50144d528dabc2cf2fd53c0f0c63a823a1, c3ab92542475d59ae685cbb294e70ca4d0ba38e9, aa0a37b5024d921e96ac4f8f487c8bfbf1f1a582 +2

Exploitation evidence

Disclosed: evidence found.
CVE published 23 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ baf8532a147d5b76681ce040e2c8f25a3f0e718d, < f2795c50144d528dabc2cf2fd53c0f0c63a823a1	Fixed in f2795c50144d528dabc2cf2fd53c0f0c63a823a1
LinuxLinux	Affected ≥ baf8532a147d5b76681ce040e2c8f25a3f0e718d, < c3ab92542475d59ae685cbb294e70ca4d0ba38e9	Fixed in c3ab92542475d59ae685cbb294e70ca4d0ba38e9
LinuxLinux	Affected ≥ baf8532a147d5b76681ce040e2c8f25a3f0e718d, < aa0a37b5024d921e96ac4f8f487c8bfbf1f1a582	Fixed in aa0a37b5024d921e96ac4f8f487c8bfbf1f1a582
LinuxLinux	Affected ≥ baf8532a147d5b76681ce040e2c8f25a3f0e718d, < 810580cf60edc75c9891c2de3225e4cda78e4d9f	Fixed in 810580cf60edc75c9891c2de3225e4cda78e4d9f
LinuxLinux	Affected ≥ baf8532a147d5b76681ce040e2c8f25a3f0e718d, < 3af81770e2011c6ac7bb597a4af2e4f3591f928c	Fixed in 3af81770e2011c6ac7bb597a4af2e4f3591f928c
LinuxLinux	Affected =2.6.25	Fixed in–

AI-suggested

A fix is available and has been applied in the Linux kernel source code. The patch replaces wait_for_completion_timeout() with wait_for_completion() in the affected functions to prevent freeing memory while asynchronous requests are still in flight. Users should update to a fixed kernel version containing the commits identified by hashes f2795c50144d528dabc2cf2fd53c0f0c63a823a1, c3ab92542475d59ae685cbb294e70ca4d0ba38e9, aa0a37b5024d921e96ac4f8f487c8bfbf1f1a582, 810580cf60edc75c9891c2de3225e4cda78e4d9f, or 3af81770e2011c6ac7bb597a4af2e4f3591f928c.

Description

CVE-2026-99039 is a use-after-free vulnerability in the Linux kernel's memstick subsystem. It occurs because the subsystem frees the memstick_dev structure after a timeout without aborting in-flight asynchronous requests, leading to writes to freed memory. This flaw was fixed by replacing wait_for_completion_timeout() with wait_for_completion() to ensure requests complete before freeing memory.

Impact

This vulnerability can cause a use-after-free condition in kernel memory, leading to potential kernel crashes or memory corruption. While no public exploits or in-the-wild exploitation are known, the flaw undermines kernel stability and could be leveraged for denial of service or other attacks that manipulate kernel memory.

Summary

The vulnerability in the Linux kernel's memstick subsystem arises from the use of wait_for_completion_timeout() in memstick_alloc_card() and memstick_set_rw_addr(), which waits for device identification and address configuration requests to complete. If the timeout expires, the memstick_dev structure is freed while the host controller driver (e.g., rtsx_usb_ms) may still be processing the request asynchronously. This results in a kernel address sanitizer (KASAN) detected slab-use-after-free write when the driver writes to memory inside the freed structure. The issue is resolved by changing the code to use wait_for_completion(), ensuring the request completes before freeing the card structure. Several host controller drivers already implement their own hardware and bus timeouts, and callers rely on unconditional wait_for_completion().

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 09:58 UTC

Technical details

References

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