CVE-2026-80922: Linux Kernel Crypto RNG Vulnerability

CVE-2026-80922 Overview

CVE-2026-80922 affects the Qualcomm random number generator (qcom-rng) driver in the Linux kernel. The driver previously rejected zero as a valid output value from the hardware random number generator. This behavior made the RNG output statistically distinguishable from true random data, weakening the cryptographic guarantees expected from the entropy source. The fix ensures the driver accepts zero as a legitimate random value, preserving the uniform distribution required for cryptographic operations.

Critical Impact
The qcom-rng driver filtered out zero-valued outputs, producing a biased distribution that could weaken downstream cryptographic operations relying on the entropy source.

Affected Products

Linux kernel builds including the qcom-rng driver
Systems using Qualcomm hardware random number generators
Downstream distributions shipping affected stable kernel branches

Discovery Timeline

2026-09-09 - CVE-2026-80922 published to NVD
2026-09-09 - Last updated in NVD database

Technical Details for CVE-2026-80922

Vulnerability Analysis

The vulnerability resides in the qcom-rng driver, which interfaces with Qualcomm hardware random number generators to supply entropy to the Linux kernel crypto subsystem. The driver contained logic that treated a zero return value from the hardware as invalid and either rejected the sample or retried until a non-zero value was returned.

Zero is a valid outcome in any uniform distribution over the byte or word space. Filtering it out skews the distribution and makes the driver's output distinguishable from true random data. Cryptographic primitives that consume this entropy, including key generation and nonce derivation, depend on uniformity to maintain their security assumptions.

The fix modifies the driver to accept zero as a legitimate random value. This restores the expected uniform distribution and eliminates the statistical bias in the RNG output.

Root Cause

The root cause is an [Insecure Random Number Generation] flaw. The driver applied an incorrect validity check that treated the value 0 as an error condition rather than a legitimate output from the hardware entropy source.

Attack Vector

Exploitation requires an attacker capable of observing or influencing cryptographic material derived from the biased RNG output. The practical attack surface depends on how upstream consumers use the entropy and whether they mix it with other sources. No public proof of concept is available, and no active exploitation has been reported.

The vulnerability mechanism is described in prose only. See the Kernel Git Commit 143c740 and related stable commits for the exact code changes.

Detection Methods for CVE-2026-80922

Indicators of Compromise

No specific runtime indicators of compromise are associated with this issue, as the flaw manifests as a statistical bias rather than an observable event.
Systems running vulnerable kernel versions with the qcom-rng driver loaded are the primary population of interest.

Detection Strategies

Inventory kernel versions across the fleet and correlate against the patched stable branches referenced in the upstream commits.
Check whether the qcom-rng module is loaded on Qualcomm-based hardware using lsmod | grep qcom_rng.
Audit downstream vendor kernels and embedded firmware images for backports of the fix.

Monitoring Recommendations

Track kernel package versions through configuration management and endpoint telemetry.
Monitor vendor advisories for the specific stable series in use, including 5.x, 6.x, and long-term support branches referenced in the kernel.org commits.
Alert on unexpected kernel module load events on production hosts.

How to Mitigate CVE-2026-80922

Immediate Actions Required

Identify all Qualcomm-based Linux systems using the qcom-rng driver.
Apply the upstream kernel patches from the referenced stable commits as soon as vendor packages are available.
Prioritize systems where the kernel entropy pool is a primary source for cryptographic key generation.

Patch Information

The fix is available across multiple stable kernel branches. Reference commits include 143c74034a1c, 3c7101cfc52e, 4c0018320942, 4ef04bdc0c9f, and 813e6718a199. Apply the vendor-supplied kernel update matching your distribution and stable series.

Workarounds

Where the qcom-rng hardware source is not required, avoid registering it as a crypto entropy provider until patched kernels are deployed.
Ensure other entropy sources such as jitterentropy and CPU-based RNGs are enabled so the kernel entropy pool does not rely solely on the affected driver.
Rebuild affected embedded firmware images against a patched kernel tree before redeployment.

bash

# Verify kernel version and qcom-rng module status
uname -r
lsmod | grep qcom_rng
modinfo qcom_rng | grep -E 'filename|version'