CVE-2025-21988 fs/netfs/read_collect: add to next->prev_donated

What is CVE-2025-21988?

CVE-2025-21988 is a critical denial of service vulnerability in Linux kernel, published on 2 Apr 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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

fs/netfs/read_collect: add to next->prev_donated

If multiple subrequests donate data to the same "next" request (depending on the subrequest completion order), each of them would overwrite the `prev_donated` field, causing data corruption and a BUG() crash ("Can't donate prior to front").

Which versions are affected by CVE-2025-21988?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2025-21988?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2025-21988 being exploited?

There is no known exploitation of CVE-2025-21988 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2025-21988, DEBIAN-CVE-2025-21988, GHSA-pvv9-vqm2-p5fx, ROOT-OS-DEBIAN-13-CVE-2025-21988, UBUNTU-CVE-2025-21988.