fork: release the files of a failed fork after sched_cancel_fork()
Affects Linux kernels where a fork fails while another thread closes a bpf link fd. Fixed in 6.12.115, 6.18.60, 7.2.14, and 7.3.1.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 6.12.115, 6.18.60, 7.2.14, 7.3.1
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 6.12.115, 6.18.60, 7.2.14, 7.3.1.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 20/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Unclear
- Fix
- Fixed in 6.12.115, 6.18.60, 7.2.14, 7.3.1
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
The Linux kernel is affected, specifically its process creation code (fork) and the sched_ext/BPF scheduler interaction. A fork that fails while another thread closes a BPF link file descriptor can deadlock, which can also block all new process creation on the system.
Read the original description
In the Linux kernel, the following vulnerability has been resolved: fork: release the files of a failed fork after sched_cancel_fork() Reorder copy_process() cleanup so sched_fork() taking scx_fork_rwsem scx_pre_fork() is safe and isn't held around exiting files. Right now, a fork that fails while another thread closed the bpf link fd will deadlock against its own read side. It also blocks every fork on the system: copy_process() holds scx_fork_rwsem for read exit_files() close_files() filp_close_sync() bpf_scx_unreg() kthread_flush_work() waits for the disable work scx_root_disable() percpu_down_write(&scx_fork_rwsem) Simply release the child's files after sched_cancel_fork() dropped the lock. The task starts out as a copy of its parent so p->files points to the parent's table until copy_files() replaces it. exit_files() must not run for a fork that failed before that. Clear p->files up front so exit_files() is a no-op for those and make copy_files() set it explicitly for CLONE_FILES.
What to do
Upgrade to a fixed version: 6.12.115, 6.18.60, 7.2.14, 7.3.1.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- Linux Linux
fixed in 6.12.115; fixed in 6.18.60; fixed in 7.2.14; fixed in 7.3.1
- Linux Linux
Version range not reported
Evidence 4
- Link
- Link
- Link
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-99217
What does this mean?
A fork that fails while another thread closes a bpf link fd can leave the kernel deadlocked. A deadlocked failed fork can then block every fork on the system, which is a denial of service.Source: git.kernel.org
Am I affected, and how do I check?
Linux kernels before the fixed releases for their branch are affected: 6.12.115, 6.18.60, 7.2.14, and 7.3.1. Check your kernel version with uname -r. The bug needs a fork to fail while another thread closes a bpf link fd.Source: git.kernel.org
What should I do about it?
Update to the fixed release for your kernel branch: 6.12.115, 6.18.60, 7.2.14, or 7.3.1.Source: git.kernel.org
Is it being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data