VulnerabilityPublished 24 Jun 2026Updated 30 Oct 2026

CVE-2026-52936: Linux kernel · crypto: jitterentropy – replace long-held spinlock with mutex

Source GCVE Database

Authoritative record:CVE-2026-52936· Medium

Not known to be exploited · CVSS 5.5 Medium · fixed in ff734dbd9e2432601a6dcd167cfb0bf8a36d1880 : update Linux kernel when convenient.

Data as of 30 Oct 2026, 16:33 UTC

CVSS 3.1 base score

5.5Medium

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

Thin evidence

One scorer or none

Patch: Available – fixed in ff734dbd9e2432601a6dcd167cfb0bf8a36d1880, ec427dc5286da1ed08f2d510e2147a7581b0cb02, 18216b8ab6904753eaf31baf453cb02ecd202ba4 +3

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

Attack Vector: Local
Attack Complexity: Low
Privileges Required: Low
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: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
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 24 Jun 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.

ghsa-9hmp-j3gc-jm6j

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ bb5530e4082446aac3a3d69780cd4dbfa4520013, < ff734dbd9e2432601a6dcd167cfb0bf8a36d1880	Fixed in ff734dbd9e2432601a6dcd167cfb0bf8a36d1880
LinuxLinux	Affected ≥ bb5530e4082446aac3a3d69780cd4dbfa4520013, < ec427dc5286da1ed08f2d510e2147a7581b0cb02	Fixed in ec427dc5286da1ed08f2d510e2147a7581b0cb02
LinuxLinux	Affected ≥ bb5530e4082446aac3a3d69780cd4dbfa4520013, < 18216b8ab6904753eaf31baf453cb02ecd202ba4	Fixed in 18216b8ab6904753eaf31baf453cb02ecd202ba4
LinuxLinux	Affected ≥ bb5530e4082446aac3a3d69780cd4dbfa4520013, < 21de77d06f6b540e870e64ef5ff56be4eb8ba08f	Fixed in 21de77d06f6b540e870e64ef5ff56be4eb8ba08f
LinuxLinux	Affected ≥ bb5530e4082446aac3a3d69780cd4dbfa4520013, < 4c03e6eb98443dc4d6d422a9780034a5b75376b4	Fixed in 4c03e6eb98443dc4d6d422a9780034a5b75376b4
LinuxLinux	Affected ≥ bb5530e4082446aac3a3d69780cd4dbfa4520013, < 01d798e9feb30212952d4e992801ba6bd6a82351	Fixed in 01d798e9feb30212952d4e992801ba6bd6a82351

Description

In the Linux kernel, the following vulnerability has been resolved: crypto: jitterentropy - replace long-held spinlock with mutex jent_kcapi_random() serializes the shared jitterentropy state, but it currently holds a spinlock across the jent_read_entropy() call. That path performs expensive jitter collection and SHA3 conditioning, so parallel readers can trigger stalls as contending waiters spin for the same lock. To prevent non-preemptible lock hold, replace rng->jent_lock with a mutex so contended readers sleep instead of spinning on a shared lock held across expensive entropy generation.

References

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