VulnerabilityPublished 19 Jul 2026Updated 20 Jul 2026

CVE-2026-53394: Linux kernel · nfsd: avoid leaking pre-allocated openowner on unconfirmed retry race

Source GCVE Database

Authoritative record:CVE-2026-53394· High 7.5

Not known to be exploited · CVSS 7.5 High · fixed in c9aefb2b5f11337c9202c5bd0c45d71198449718 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.6% chance of exploitation in 30 days – higher than 49% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in c9aefb2b5f11337c9202c5bd0c45d71198449718, a10bf67fe06469a71a401f72f328237345d553c0, 57aee7a35bb12753057c5b65d72d1f46c0e95b07 +1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 19 Jul 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.

ghsa-3gwr-8cwh-87h2

What to do

Upgrade Linux kernel to c9aefb2b5f11337c9202c5bd0c45d71198449718, a10bf67fe06469a71a401f72f328237345d553c0, 57aee7a35bb12753057c5b65d72d1f46c0e95b07 or 017a6150106b054cc84d1b0582d97bd3a74d4281.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 23df17788c6212809848f836b10c4f85b16843a5, < c9aefb2b5f11337c9202c5bd0c45d71198449718	Fixed in c9aefb2b5f11337c9202c5bd0c45d71198449718
LinuxLinux	Affected ≥ 23df17788c6212809848f836b10c4f85b16843a5, < a10bf67fe06469a71a401f72f328237345d553c0	Fixed in a10bf67fe06469a71a401f72f328237345d553c0
LinuxLinux	Affected ≥ 23df17788c6212809848f836b10c4f85b16843a5, < 57aee7a35bb12753057c5b65d72d1f46c0e95b07	Fixed in 57aee7a35bb12753057c5b65d72d1f46c0e95b07
LinuxLinux	Affected ≥ 23df17788c6212809848f836b10c4f85b16843a5, < 017a6150106b054cc84d1b0582d97bd3a74d4281	Fixed in 017a6150106b054cc84d1b0582d97bd3a74d4281
LinuxLinux	Affected =6.10	Fixed in–

AI-suggested

A fix has been implemented in the Linux kernel to address this vulnerability by changing the retry logic to reuse allocated objects and prevent memory leaks. Users should apply the official kernel updates or patches that include this fix. Since this is a kernel-level issue, updating to a patched kernel version is the recommended remediation. Patch status is not explicitly confirmed in the provided data; check the vendor or Linux kernel advisory for the current remediation guidance.

Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: avoid leaking pre-allocated openowner on unconfirmed retry race When find_or_alloc_open_stateowner() encounters an unconfirmed owner, it calls release_openowner() and sets oo = NULL. Control then falls through past the `if (oo)` guard -- which would have freed any pre-allocated `new` -- and unconditionally executes `new = alloc_stateowner(...)`. If `new` was already allocated on a prior iteration, the pointer is silently overwritten and the previous allocation (slab object + owner name buffer) is leaked. This requires a race: two NFSv4.0 OPEN threads with the same owner string, where a concurrent thread inserts a new unconfirmed owner into the hash between retry iterations. The window is narrow but repeatable under adversarial conditions. Fix by adding `goto retry` after `oo = NULL` so the already-allocated `new` is reused on the next iteration rather than overwritten.

Impact

The vulnerability causes a memory leak in the Linux kernel's NFS server under specific race conditions involving concurrent NFSv4.0 OPEN requests with the same owner string. While the window for exploitation is narrow, repeated triggering under adversarial conditions can lead to resource exhaustion or degraded service availability due to leaked memory allocations.

Summary

The Linux kernel's nfsd component had a vulnerability (CVE-2026-53394) where the function find_or_alloc_open_stateowner() could leak memory due to a race condition. When encountering an unconfirmed owner, the code would release the openowner and set the pointer to NULL but then proceed to allocate a new stateowner unconditionally, overwriting the pointer to a previously allocated object and causing a memory leak. This race requires two concurrent NFSv4.0 OPEN threads with the same owner string and a concurrent insertion of a new unconfirmed owner between retry attempts. The fix adds a retry jump to reuse the already allocated object, preventing the leak.

References

Community reviews

Loading reviews…