CVE-2026-74438
Received Received - Intake

Removal of Insecure RNG in Linux Kernel Sun4i-SS

Publication date: 2026-08-15

Last updated on: 2026-08-15

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: crypto: sun4i-ss - Remove insecure and unused rng_alg Remove sun4i_ss_rng, as it is insecure and unused: - It has multiple vulnerabilities. sun4i_ss_prng_seed() is missing locking and has a buffer overflow. sun4i_ss_prng_generate() fails to fill the entire buffer with cryptographic random bytes, because it rounds the destination length down and also doesn't actually wait for the hardware to be ready before pulling bytes from it. - No user of this code is known. It's usable only theoretically via the "rng" algorithm type of AF_ALG. But userspace actually just uses the actual Linux RNG (/dev/random etc) instead. And rng_algs don't contribute entropy to the actual Linux RNG either. (This may have been confused with hwrng, which does contribute entropy.) The sun4i_ss_prng_seed() buffer overflow was reported by Tianchu Chen and discovered by Atuin - Automated Vulnerability Discovery Engine There's no point in fixing all these vulnerabilities individually when this is unused code, so let's just remove it.

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Meta Information

Published
2026-08-15
Last Modified
2026-08-15
Generated
2026-08-15
AI Q&A
2026-08-15
EPSS Evaluated
N/A
NVD
CVE-2026-74438
EUVD
EUVD-2026-59585

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability involves the Linux kernel's sun4i-ss cryptographic module, specifically the insecure and unused rng_alg component called sun4i_ss_rng. The code had multiple issues like missing locking in sun4i_ss_prng_seed() and a buffer overflow, while sun4i_ss_prng_generate() failed to fill buffers properly with random bytes. Since no userspace applications rely on this code, it was removed entirely instead of fixing individual vulnerabilities.

Detection Guidance

This vulnerability is specific to the Linux kernel's sun4i-ss cryptographic module. Detection involves checking if the vulnerable module is loaded. Run: lsmod | grep sun4i_ss. If the module is present, it may indicate exposure to the vulnerability.

Impact Analysis

This vulnerability likely has minimal direct impact on most users because the affected code (sun4i_ss_rng) was unused in practice. Users relying on the Linux kernel's standard random number generation (/dev/random) are unaffected. The vulnerability only affected theoretical usage via the AF_ALG interface, which is not commonly used.

Mitigation Strategies

Immediately unload the sun4i_ss module using rmmod sun4i_ss. To prevent reloading, blacklist the module by adding 'blacklist sun4i_ss' to /etc/modprobe.d/blacklist.conf. Update the Linux kernel to a patched version where this module is removed.

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