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Linux Kernel CVE-2026-74436

| EUVDEUVD-2026-59583 CRITICAL
2026-08-15 Linux GHSA-c43x-9gq9-q65m
Critical
Disputed · 9.8 Vendor: Linux
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Severity by source

Sources disagree (Medium–Critical)
Vendor (Linux) PRIMARY
9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI
5.8 MEDIUM

Kernel-internal use-after-free won only by racing socket teardown, so AV:L/AC:H and PR:L for local access; impact is chiefly a crash (A:H) with limited, unproven C/I.

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

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorVendor: Linux

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

5
Analysis Generated
Aug 17, 2026 - 11:22 vuln.today
CVSS changed
Aug 17, 2026 - 06:22 NVD
9.8 (CRITICAL)
Patch available
Aug 15, 2026 - 07:19 EUVD
CVE Published
Aug 15, 2026 - 05:59 cve.org
CRITICAL 9.8
CVE Published
Aug 15, 2026 - 05:59 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

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

rxrpc: serialize kernel accept preallocation with socket teardown

rxrpc_kernel_charge_accept() reads rx->backlog without any socket/backlog synchronization and passes that raw pointer into rxrpc_service_prealloc_one(). A concurrent rxrpc_discard_prealloc() sets rx->backlog = NULL and frees the backlog rings, so a kernel preallocation worker can keep using a freed struct rxrpc_backlog while updating *_backlog_head/tail and array slots.

Serialize the state check and backlog lookup with the socket lock, and reject kernel preallocation once teardown has disabled listening or discarded the service backlog.

AnalysisAI

Use-after-free in the Linux kernel's AF_RXRPC (rxrpc) networking subsystem lets a freed struct rxrpc_backlog be reused when kernel accept preallocation races against socket teardown. The flaw affects kernels using the rxrpc transport (notably kAFS/AFS clients) prior to the fixed stable releases; a kernel worker calling rxrpc_kernel_charge_accept() reads rx->backlog with no lock while rxrpc_discard_prealloc() concurrently NULLs and frees it, corrupting backlog head/tail pointers and array slots. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Reach host running rxrpc/kAFS
Delivery
Trigger concurrent accept preallocation and teardown
Exploit
Race frees rx->backlog while in use
Execution
Kernel writes into freed rxrpc_backlog
Impact
Memory corruption and kernel crash (DoS)

Vulnerability AssessmentAI

Exploitation Exploitation requires the target to actually use the rxrpc/AF_RXRPC transport (typically via the kAFS/AFS filesystem or another in-kernel RxRPC consumer) - on systems where the rxrpc module is never loaded there is no attack surface. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The supplied CVSS 9.8 (AV:N/AC:L/PR:N/UI:N) appears to be an automated worst-case score that overstates real-world exploitability: this is a kernel-internal race between a preallocation worker and socket teardown, not a directly remote-triggerable memory-corruption primitive, so a more realistic vector is local with high attack complexity (winning a narrow race window) - verify against vendor before treating as remotely unauthenticated. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario On a host actively using kAFS/rxrpc, a local attacker (or a fault-injection workload) repeatedly opens, listens on, and tears down rxrpc service sockets while kernel accept preallocation is charging the backlog, aiming to win the race where rx->backlog is freed but still in use. Hitting the window corrupts freed kernel memory, most reliably crashing the kernel (DoS) and potentially enabling further memory manipulation. …
Remediation Upgrade to a fixed stable kernel: Vendor-released patch 6.6.148, 6.12.101, 6.18.40, or 7.1.5 (mainline 7.2-rc1), or your distribution's equivalent backport containing the rxrpc serialization commits from git.kernel.org (0337cdba0c47 / dfa0b2bbc5e5 / 35a967ff8b24 / 1741378a7a83 / dc175389b18c). … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 24 hours, identify all systems running vulnerable Linux kernel versions (prior to the fixed stable releases noted in vendor advisory) and conduct patch testing in a non-production AFS client environment. …

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Vendor StatusVendor

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CVE-2026-74436 vulnerability details – vuln.today

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