CVE-2021-46935

MEDIUM
Published Feb 27, 2024 Modified Nov 21, 2024 CWE-668

Description

In the Linux kernel, the following vulnerability has been resolved: binder: fix async_free_space accounting for empty parcels In 4.13, commit 74310e06be4d ("android: binder: Move buffer out of area shared with user space") fixed a kernel structure visibility issue. As part of that patch, sizeof(void *) was used as the buffer size for 0-length data payloads so the driver could detect abusive clients sending 0-length asynchronous transactions to a server by enforcing limits on async_free_size. Unfortunately, on the "free" side, the accounting of async_free_space did not add the sizeof(void *) back. The result was that up to 8-bytes of async_free_space were leaked on every async transaction of 8-bytes or less. These small transactions are uncommon, so this accounting issue has gone undetected for several years. The fix is to use "buffer_size" (the allocated buffer size) instead of "size" (the logical buffer size) when updating the async_free_space during the free operation. These are the same except for this corner case of asynchronous transactions with payloads < 8 bytes.

Is your site exposed to CVE-2021-46935?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

5.5
MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Weakness Type (CWE)

CWE-668 CWE-668

Affected Products

Vendor Product
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel

References

Advisories & Patches

https://git.kernel.org/stable/c/103b16a8c51f96d5fe063022869ea906c256e5da https://git.kernel.org/stable/c/17691bada6b2f1d5f1c0f6d28cd9d0727023b0ff https://git.kernel.org/stable/c/1cb8444f3114f0bb2f6e3bcadcf09aa4a28425d4 https://git.kernel.org/stable/c/2d2df539d05205fd83c404d5f2dff48d36f9b495 https://git.kernel.org/stable/c/7c7064402609aeb6fb11be1b4ec10673ff17b593 https://git.kernel.org/stable/c/cfd0d84ba28c18b531648c9d4a35ecca89ad9901 https://git.kernel.org/stable/c/103b16a8c51f96d5fe063022869ea906c256e5da https://git.kernel.org/stable/c/17691bada6b2f1d5f1c0f6d28cd9d0727023b0ff https://git.kernel.org/stable/c/1cb8444f3114f0bb2f6e3bcadcf09aa4a28425d4 https://git.kernel.org/stable/c/2d2df539d05205fd83c404d5f2dff48d36f9b495 https://git.kernel.org/stable/c/7c7064402609aeb6fb11be1b4ec10673ff17b593 https://git.kernel.org/stable/c/cfd0d84ba28c18b531648c9d4a35ecca89ad9901

Frequently Asked Questions

What is CVE-2021-46935? +
In the Linux kernel, the following vulnerability has been resolved: binder: fix async_free_space accounting for empty parcels In 4.13, commit 74310e06be4d ("android: binder: Move buffer out of area shared with user space") fixed a kernel structure visibility issue. As part of that patch, sizeof(void *) was used as the buffer size for 0-length data payloads so the driver could detect abusive clients sending 0-length asynchronous transactions to a server by enforcing limits on async_free_size. Unfortunately, on the "free" side, the accounting of async_free_space did not add the sizeof(void *) back. The result was that up to 8-bytes of async_free_space were leaked on every async transaction of 8-bytes or less. These small transactions are uncommon, so this accounting issue has gone undetected for several years. The fix is to use "buffer_size" (the allocated buffer size) instead of "size" (the logical buffer size) when updating the async_free_space during the free operation. These are the same except for this corner case of asynchronous transactions with payloads < 8 bytes. It has a CVSS v3.1 base score of 5.5 (MEDIUM).
How severe is CVE-2021-46935? +
CVE-2021-46935 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.
What products are affected by CVE-2021-46935? +
CVE-2021-46935 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.
How do I check if I'm vulnerable to CVE-2021-46935? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2025-54502

Incorrect use of boot service in the AMD Platform Configuration Blob (APCB) SMM driver could allow a privileged attacker with …
CVE-2026-47141

vm2 is an open source vm/sandbox for Node.js. Prior to version 3.11.4, NodeVM exposes some process-wide observability builtins when they …
CVE-2025-23205

nbgrader is a system for assigning and grading notebooks. Enabling frame-ancestors: 'self' grants any JupyterHub user the ability to extract …
CVE-2025-32428

Jupyter Remote Desktop Proxy allows you to run a Linux Desktop on a JupyterHub. jupyter-remote-desktop-proxy was meant to rely on …
CVE-2025-3651

Improper Verification of Source of a Communication Channel in Work Desktop for Mac versions 10.8.1.46 and earlier allows attackers to …
CVE-2025-34064

A cloud infrastructure misconfiguration in OneLogin AD Connector results in log data being sent to a hardcoded S3 bucket (onelogin-adc-logs-production) …

Don't wait for an exploit

Scan your website for vulnerabilities like CVE-2021-46935 — free, no signup required.