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Linux Kernel CVE-2026-64306

| EUVDEUVD-2026-49018 MEDIUM
2026-07-25 Linux GHSA-9h5h-wjm4-4jqg
Denial Of Service Linux Red Hat Suse
5.5
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
vuln.today AI
5.5 MEDIUM

Local low-privilege access triggers an error path with no confidentiality or integrity impact; only kernel availability is affected via uninitialised buffer consumption.

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0 AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
MEDIUM
qualitative
Red Hat
7.0 MEDIUM
qualitative

Primary rating from NVD.

CVSS VectorNVD

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

Lifecycle Timeline

6
Metadata Corrected
Sep 03, 2026 - 18:40 vuln.today
tag: Information Disclosure replaced by Denial Of Service
Analysis Generated
Sep 03, 2026 - 18:16 vuln.today
CVSS changed
Sep 03, 2026 - 16:07 NVD
5.5 (MEDIUM)
Patch available
Jul 25, 2026 - 11:18 EUVD
CVE Published
Jul 25, 2026 - 08:49 cve.org
UNKNOWN (no severity yet)
CVE Published
Jul 25, 2026 - 08:49 nvd
MEDIUM 5.5

DescriptionNVD

In the Linux kernel, the following vulnerability has been resolved:

crypto: drbg - Fix returning success on failure in CTR_DRBG

drbg_ctr_generate() sometimes returns success when it fails, leaving the output buffer uninitialized. Fix it.

AnalysisAI

Silent error propagation in the Linux kernel's CTR_DRBG implementation (drbg_ctr_generate()) causes the function to return a success code while leaving its output buffer uninitialized when an internal operation fails. Code that relies on the generated random material receives garbage data, which can trigger kernel crashes or hangs depending on how the uninitialized buffer is consumed downstream. No public exploit has been identified; patched stable kernel releases are available across all active longterm-support branches.

Technical ContextAI

The CTR_DRBG (Counter mode Deterministic Random Bit Generator, NIST SP 800-90A) is a primary DRBG implementation in the Linux kernel's crypto/drbg.c, used for cryptographically secure random number generation by in-kernel callers including TLS stacks and key-generation routines. The defect is an incorrect return-value propagation in drbg_ctr_generate(): on an internal error, the function exits a code path that sets the return value to 0 (success) instead of the error code, leaving the caller's output buffer uninitialised. No CWE is assigned in the source data, but the root cause maps closely to CWE-252 (Unchecked Return Value) or CWE-755 (Improper Handling of Exceptional Conditions). The CPE cpe:2.3:a:linux:linux:* covers all affected mainline and stable-tree versions.

RemediationAI

Apply the applicable patched stable kernel release for your branch: 5.10.261 or later (5.10.x), 5.15.212 or later (5.15.x), 6.1.178 or later (6.1.x), 6.6.145 or later (6.6.x), 6.12.96 or later (6.12.x), 6.18.39 or later (6.18.x), or 7.1.4 or later (7.1.x). Individual stable-tree fix commits are available at git.kernel.org/stable - representative commits include https://git.kernel.org/stable/c/074db6db03a0aaa78f05ca9d4838053713796665 and https://git.kernel.org/stable/c/75597e8774f319152744d24e0683d9393540a951. Distribution users (RHEL, Debian, Ubuntu, SUSE) should apply kernel updates through their standard package manager, as maintainers will backport the fix. No workaround is feasible that disables the CTR_DRBG error path without removing cryptographic functionality.

Same technique Denial Of Service

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
Container suse/sl-micro/6.0/base-os-container:2.1.3-7.208 Container suse/sl-micro/6.1/base-os-container:2.2.1-5.184 Affected
Container suse/sl-micro/6.0/kvm-os-container:2.1.3-6.218 Container suse/sl-micro/6.1/kvm-os-container:2.2.1-5.186 Affected
Container suse/sl-micro/6.0/rt-os-container:2.1.3-7.237 Container suse/sl-micro/6.1/rt-os-container:2.2.1-5.180 Affected
SUSE Linux Enterprise Real Time 15 SP7 SUSE Real Time Module 15 SP7 Fixed
SUSE Linux Micro 6.0 Fixed

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CVE-2026-64306 vulnerability details – vuln.today
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