{"cve":"CVE-2021-46935","nvd":{"published":"2024-02-27T10:15:07.957","modified":"2026-06-17T04:15:54.380","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbinder: fix async_free_space accounting for empty parcels\n\nIn 4.13, commit 74310e06be4d (\"android: binder: Move buffer out of area shared with user space\")\nfixed a kernel structure visibility issue. As part of that patch,\nsizeof(void *) was used as the buffer size for 0-length data payloads so\nthe driver could detect abusive clients sending 0-length asynchronous\ntransactions to a server by enforcing limits on async_free_size.\n\nUnfortunately, on the \"free\" side, the accounting of async_free_space\ndid not add the sizeof(void *) back. The result was that up to 8-bytes of\nasync_free_space were leaked on every async transaction of 8-bytes or\nless.  These small transactions are uncommon, so this accounting issue\nhas gone undetected for several years.\n\nThe fix is to use \"buffer_size\" (the allocated buffer size) instead of\n\"size\" (the logical buffer size) when updating the async_free_space\nduring the free operation. These are the same except for this\ncorner case of asynchronous transactions with payloads < 8 bytes.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N","score":5.5},"cwes":["CWE-668"],"references":["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"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:45:59.823092188+00:00"},"epss":{"cve":"CVE-2021-46935","score":0.00229,"percentile":0.13775,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}