# CVE-2025-39782: jbd2: prevent softlockup in jbd2_log_do_checkpoint()

> A missing rescheduling call in the Linux kernel's jbd2 module can cause a soft lockup, leading to system unavailability.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Sep 2025
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-74676, BELL-CVE-2025-39782, DEBIAN-CVE-2025-39782, GHSA-38p5-w7j2-vwrv, ROOT-OS-DEBIAN-11-CVE-2025-39782, ROOT-OS-DEBIAN-12-CVE-2025-39782, ROOT-OS-DEBIAN-13-CVE-2025-39782, ROOT-OS-UBUNTU-2204-CVE-2025-39782, ROOT-OS-UBUNTU-2404-CVE-2025-39782, UBUNTU-CVE-2025-39782

## What is CVE-2025-39782?

CVE-2025-39782 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 11 Sep 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

jbd2: prevent softlockup in jbd2_log_do_checkpoint()

Both jbd2_log_do_checkpoint() and jbd2_journal_shrink_checkpoint_list()
periodically release j_list_lock after processing a batch of buffers to
avoid long hold times on the j_list_lock. However, since both functions
contend for j_list_lock, the combined time spent waiting and processing
can be significant.

jbd2_journal_shrink_checkpoint_list() explicitly calls cond_resched() when
need_resched() is true to avoid softlockups during prolonged operations.
But jbd2_log_do_checkpoint() only exits its loop when need_resched() is
true, relying on potentially sleeping functions like __flush_batch() or
wait_on_buffer() to trigger rescheduling. If those functions do not sleep,
the kernel may hit a softlockup.

watchdog: BUG: soft lockup - CPU#3 stuck for 156s! [kworker/u129:2:373]
CPU: 3 PID: 373 Comm: kworker/u129:2 Kdump: loaded Not tainted 6.6.0+ #10
Hardware name: Huawei TaiShan 2280 /BC11SPCD, BIOS 1.27 06/13/2017
Workqueue: writeback wb_workfn (flush-7:2)
pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : native_queued_spin_lock_slowpath+0x358/0x418
lr : jbd2_log_do_checkpoint+0x31c/0x438 [jbd2]
Call trace:
 native_queued_spin_lock_slowpath+0x358/0x418
 jbd2_log_do_checkpoint+0x31c/0x438 [jbd2]
 __jbd2_log_wait_for_space+0xfc/0x2f8 [jbd2]
 add_transaction_credits+0x3bc/0x418 [jbd2]
 start_this_handle+0xf8/0x560 [jbd2]
 jbd2__journal_start+0x118/0x228 [jbd2]
 __ext4_journal_start_sb+0x110/0x188 [ext4]
 ext4_do_writepages+0x3dc/0x740 [ext4]
 ext4_writepages+0xa4/0x190 [ext4]
 do_writepages+0x94/0x228
 __writeback_single_inode+0x48/0x318
 writeback_sb_inodes+0x204/0x590
 __writeback_inodes_wb+0x54/0xf8
 wb_writeback+0x2cc/0x3d8
 wb_do_writeback+0x2e0/0x2f8
 wb_workfn+0x80/0x2a8
 process_one_work+0x178/0x3e8
 worker_thread+0x234/0x3b8
 kthread+0xf0/0x108
 ret_from_fork+0x10/0x20

So explicitly call cond_resched() in jbd2_log_do_checkpoint() to avoid
softlockup.

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2025-39782?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2025-39782?

Apply the vendor's patch.

## Is CVE-2025-39782 being exploited?

There is no known exploitation of CVE-2025-39782 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-39782 and fix it if it is affected.

What it is: CVE-2025-39782 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 11 Sep 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-39782 in the wild and no public exploit code.

Affected product: Debian Debian Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-39782/ (Markdown: https://insights.sbomify.com/CVE-2025-39782/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-39782
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-39782
- OSV: https://osv.dev/vulnerability/CVE-2025-39782

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-39782/
Summaries are generated and may contain mistakes; the official description above is the record.