CVE-2026-63816: In the Linux kernel, the following vulnerability has been resolved: f2fs: atomic: fix UAF issue on f2fs_inode_info.atomic_inode - ioctl(F2FS_IOC_GARBAGE_COLLECT_RANGE) - shrink
In the Linux kernel, the following vulnerability has been resolved:
f2fs: atomic: fix UAF issue on f2fs_inode_info.atomic_inode
- ioctl(F2FS_IOC_GARBAGE_COLLECT_RANGE) - shrink
- f2fs_gc
- gc_data_segment
- ra_data_block(cow_inode)
- mapping = F2FS_I(inode)->atomic_inode->i_mapping
: f2fs_is_cow_file(cow_inode) is true
- f2fs_evict_inode(atomic_inode)
- clear_inode_flag(fi->cow_inode, FI_COW_FILE)
- F2FS_I(fi->cow_inode)->atomic_inode = NULL
...
- truncate_inode_pages_final(atomic_inode)
- f2fs_grab_cache_folio(mapping)
: create folio in atomic_inode->mapping
- clear_inode(atomic_inode)
- BUG_ON(atomic_inode->i_data.nrpages)
We need to add a reference on fi->atomic_inode before using its mapping
field during garbage collection, otherwise, it will cause UAF issue.
Details
Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-63816
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Low exploitation riskCVE-2026-638160.12% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 2% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-63816 | coverage & exploitation status | NVD · CVE.org |
Same CVEs, other sources
How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.
- unknownMultiple vulnerabilities in Debian Linux kernel (July 24, 2026)cert-fr-avis
- unknownDSA-6393-1 linux - security updatedebian
- criticalCVE-2026-63816: f2fs: atomic: fix UAF issue on f2fs_inode_info.atomic_inodemsrc
Recent advisories for In the Linux
A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.
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- medium[UPDATE] [medium] Linux Kernel: Multiple vulnerabilities allow Denial of Servicecert-bund · 2026-07-31
- medium[UPDATE] [medium] Linux Kernel: Multiple vulnerabilitiescert-bund · 2026-07-31
- medium[UPDATE] [medium] Linux Kernel: Multiple vulnerabilities allow denial of servicecert-bund · 2026-07-31
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