Linux Kernel up to 6.1.8 bpf_ringbuf_output type confusion

Summaryinfo

A vulnerability classified as critical was found in Linux Kernel up to 4.19.271/5.4.230/5.10.165/5.15.90/6.1.8. This impacts the function bpf_ringbuf_output. The manipulation results in type confusion. This vulnerability was named CVE-2023-53024. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 4.19.271/5.4.230/5.10.165/5.15.90/6.1.8. Affected is the function bpf_ringbuf_output. The manipulation with an unknown input leads to a type confusion vulnerability. CWE is classifying the issue as CWE-843. The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix pointer-leak due to insufficient speculative store bypass mitigation To mitigate Spectre v4, 2039f26f3aca ("bpf: Fix leakage due to insufficient speculative store bypass mitigation") inserts lfence instructions after 1) initializing a stack slot and 2) spilling a pointer to the stack. However, this does not cover cases where a stack slot is first initialized with a pointer (subject to sanitization) but then overwritten with a scalar (not subject to sanitization because the slot was already initialized). In this case, the second write may be subject to speculative store bypass (SSB) creating a speculative pointer-as-scalar type confusion. This allows the program to subsequently leak the numerical pointer value using, for example, a branch-based cache side channel. To fix this, also sanitize scalars if they write a stack slot that previously contained a pointer. Assuming that pointer-spills are only generated by LLVM on register-pressure, the performance impact on most real-world BPF programs should be small. The following unprivileged BPF bytecode drafts a minimal exploit and the mitigation: [...] // r6 = 0 or 1 (skalar, unknown user input) // r7 = accessible ptr for side channel // r10 = frame pointer (fp), to be leaked // r9 = r10 # fp alias to encourage ssb *(u64 *)(r9 - 8) = r10 // fp[-8] = ptr, to be leaked // lfence added here because of pointer spill to stack. // // Ommitted: Dummy bpf_ringbuf_output() here to train alias predictor // for no r9-r10 dependency. // *(u64 *)(r10 - 8) = r6 // fp[-8] = scalar, overwrites ptr // 2039f26f3aca: no lfence added because stack slot was not STACK_INVALID, // store may be subject to SSB // // fix: also add an lfence when the slot contained a ptr // r8 = *(u64 *)(r9 - 8) // r8 = architecturally a scalar, speculatively a ptr // // leak ptr using branch-based cache side channel: r8 &= 1 // choose bit to leak if r8 == 0 goto SLOW // no mispredict // architecturally dead code if input r6 is 0, // only executes speculatively iff ptr bit is 1 r8 = *(u64 *)(r7 + 0) # encode bit in cache (0: slow, 1: fast) SLOW: [...] After running this, the program can time the access to *(r7 + 0) to determine whether the chosen pointer bit was 0 or 1. Repeat this 64 times to recover the whole address on amd64. In summary, sanitization can only be skipped if one scalar is overwritten with another scalar. Scalar-confusion due to speculative store bypass can not lead to invalid accesses because the pointer bounds deducted during verification are enforced using branchless logic. See 979d63d50c0c ("bpf: prevent out of bounds speculation on pointer arithmetic") for details. Do not make the mitigation depend on !env->allow_{uninit_stack,ptr_leaks} because speculative leaks are likely unexpected if these were enabled. For example, leaking the address to a protected log file may be acceptable while disabling the mitigation might unintentionally leak the address into the cached-state of a map that is accessible to unprivileged processes.

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2023-53024 since 03/27/2025. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 01/23/2026).

The vulnerability scanner Nessus provides a plugin with the ID 241018 (EulerOS 2.0 SP13 : kernel (EulerOS-SA-2025-1704)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 4.19.272, 5.4.231, 5.10.166, 5.15.91 or 6.1.9 eliminates this vulnerability. Applying the patch aae109414a57ab4164218f36e2e4a17f027fcaaa/81b3374944d201872cfcf82730a7860f8e7c31dd/da75dec7c6617bddad418159ffebcb133f008262/01bdcc73dbe7be3ad4d4ee9a59b71e42f461a528/b0c89ef025562161242a7c19b213bd6b272e93df/e4f4db47794c9f474b184ee1418f42e6a07412b6 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (241018), EUVD (EUVD-2023-59696) and CERT Bund (WID-SEC-2025-0649). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

• Google Container-Optimized OS
• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• Dell Avamar
• Open Source Linux Kernel
• SolarWinds Security Event Manager
• Dell NetWorker
• Dell Secure Connect Gateway

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 4.19.271
• 5.4.230
• 5.10.165
• 5.15.0
• 5.15.1
• 5.15.2
• 5.15.3
• 5.15.4
• 5.15.5
• 5.15.6
• 5.15.7
• 5.15.8
• 5.15.9
• 5.15.10
• 5.15.11
• 5.15.12
• 5.15.13
• 5.15.14
• 5.15.15
• 5.15.16
• 5.15.17
• 5.15.18
• 5.15.19
• 5.15.20
• 5.15.21
• 5.15.22
• 5.15.23
• 5.15.24
• 5.15.25
• 5.15.26
• 5.15.27
• 5.15.28
• 5.15.29
• 5.15.30
• 5.15.31
• 5.15.32
• 5.15.33
• 5.15.34
• 5.15.35
• 5.15.36
• 5.15.37
• 5.15.38
• 5.15.39
• 5.15.40
• 5.15.41
• 5.15.42
• 5.15.43
• 5.15.44
• 5.15.45
• 5.15.46
• 5.15.47
• 5.15.48
• 5.15.49
• 5.15.50
• 5.15.51
• 5.15.52
• 5.15.53
• 5.15.54
• 5.15.55
• 5.15.56
• 5.15.57
• 5.15.58
• 5.15.59
• 5.15.60
• 5.15.61
• 5.15.62
• 5.15.63
• 5.15.64
• 5.15.65
• 5.15.66
• 5.15.67
• 5.15.68
• 5.15.69
• 5.15.70
• 5.15.71
• 5.15.72
• 5.15.73
• 5.15.74
• 5.15.75
• 5.15.76
• 5.15.77
• 5.15.78
• 5.15.79
• 5.15.80
• 5.15.81
• 5.15.82
• 5.15.83
• 5.15.84
• 5.15.85
• 5.15.86
• 5.15.87
• 5.15.88
• 5.15.89
• 5.15.90
• 6.1.0
• 6.1.1
• 6.1.2
• 6.1.3
• 6.1.4
• 6.1.5
• 6.1.6
• 6.1.7
• 6.1.8

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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