PT-2026-61120 · Linux · Linux Kernel

CVE-2026-63804 · Published 2026-07-19 · Updated 2026-07-19

Positive Technologies (AI Summary)

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description A use-after-free issue exists in the GFS2 file system within the gfs2 qd dealloc() function. This function is executed as an RCU (Read-Copy-Update) callback—a mechanism used to synchronize access to data—and accesses the superblock object sdp via qd->qd sbd after the quota object qd has been freed. During the unmount process, if the timeout for sd kill wait expires or if gfs2 gl hash clear() schedules additional callbacks, the gfs2 put super() function may free the superblock before the pending RCU callbacks have finished executing.

Recommendations As a temporary mitigation, restrict the use of GFS2 quota features until the system is updated. At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Related Identifiers

CVE-2026-63804

Affected Products

Linux Kernel

References · 7

• https://nvd.nist.gov/vuln/detail/CVE-2026-63804 · Security Note
• https://twitter.com/VulmonFeeds/status/2078904834783084578 · Twitter Post
• https://git.kernel.org/stable/c/b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0 · Note
• https://git.kernel.org/stable/c/f9c9ec2c319f843b70ecdf939d48b52d189bc081 · Note
• https://git.kernel.org/stable/c/4fe388218826df8607ae41a6305df67db08a9093 · Note
• https://git.kernel.org/stable/c/8745d9f7e1682c39f0a1578895ac74205e2a6757 · Note
• https://git.kernel.org/stable/c/9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0 · Note