CVE-2026-63802
blk-cgroup: fix UAF in __blkcg_rstat_flush()
Description
In the Linux kernel, the following vulnerability has been resolved: blk-cgroup: fix UAF in __blkcg_rstat_flush() When multiple blkgs in the same blkcg are released concurrently, a use-after-free can occur. The race happens when one blkg's __blkcg_rstat_flush() removes another blkg's iostat entries via llist_del_all(). The second blkg sees an empty list and proceeds to free itself while the first is still iterating over its entries. Move the flush from __blkg_release() (RCU callback) to blkg_release() (before call_rcu). This ensures the RCU grace period waits for any concurrent flush's rcu_read_lock() section to complete before freeing.
INFO
Published Date :
July 19, 2026, 12:16 p.m.
Last Modified :
July 19, 2026, 12:16 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products
The following products are affected by CVE-2026-63802
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Apply the provided Linux kernel patch.
- Update the affected Linux kernel version.
- Ensure RCU grace periods complete before freeing.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-63802.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-63802 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-63802
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-63802 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-63802 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jul. 19, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '20cb1c2fb7568a6054c55defe044311397e01ddb', 'lessThan': '96e545410c4f74c89d496c1d5d9ef8d08f14368b', 'versionType': 'git'}, {'status': 'affected', 'version': '20cb1c2fb7568a6054c55defe044311397e01ddb', 'lessThan': 'bbebd9425cad3573d1527441753899b926525a0f', 'versionType': 'git'}, {'status': 'affected', 'version': '20cb1c2fb7568a6054c55defe044311397e01ddb', 'lessThan': '5e5b7f2ef854936e95dceb6a2fdfefcb7152d2c6', 'versionType': 'git'}, {'status': 'affected', 'version': '20cb1c2fb7568a6054c55defe044311397e01ddb', 'lessThan': 'afebe44facc48a61761e885bbb7f0380d4a603ec', 'versionType': 'git'}, {'status': 'affected', 'version': '20cb1c2fb7568a6054c55defe044311397e01ddb', 'lessThan': '0ab5ee5a1badb58cbb2242617cb01a4972b1f2a2', 'versionType': 'git'}, {'status': 'affected', 'version': '0f6090d90f627d8c58f939067d6c6821ce1b3c68', 'versionType': 'git'}, {'status': 'affected', 'version': '6.3.9', 'lessThan': '6.4', 'versionType': 'semver'}], 'programFiles': ['block/blk-cgroup.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6.4'}, {'status': 'unaffected', 'version': '0', 'lessThan': '6.4', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.6.144', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.95', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.38', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.3', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['block/blk-cgroup.c'], 'defaultStatus': 'affected'}] Added Description In the Linux kernel, the following vulnerability has been resolved: blk-cgroup: fix UAF in __blkcg_rstat_flush() When multiple blkgs in the same blkcg are released concurrently, a use-after-free can occur. The race happens when one blkg's __blkcg_rstat_flush() removes another blkg's iostat entries via llist_del_all(). The second blkg sees an empty list and proceeds to free itself while the first is still iterating over its entries. Move the flush from __blkg_release() (RCU callback) to blkg_release() (before call_rcu). This ensures the RCU grace period waits for any concurrent flush's rcu_read_lock() section to complete before freeing. Added Reference https://git.kernel.org/stable/c/0ab5ee5a1badb58cbb2242617cb01a4972b1f2a2 Added Reference https://git.kernel.org/stable/c/5e5b7f2ef854936e95dceb6a2fdfefcb7152d2c6 Added Reference https://git.kernel.org/stable/c/96e545410c4f74c89d496c1d5d9ef8d08f14368b Added Reference https://git.kernel.org/stable/c/afebe44facc48a61761e885bbb7f0380d4a603ec Added Reference https://git.kernel.org/stable/c/bbebd9425cad3573d1527441753899b926525a0f