CVE-2025-68794 iomap: adjust read range correctly for non-block-aligned positions
An integer underflow in the Linux kernel iomap subsystem can cause incorrect read ranges, potentially leading to a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-68794?
CVE-2025-68794 is a critical vulnerability in Linux, published on 13 Jan 2026. 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:
iomap: adjust read range correctly for non-block-aligned positions
iomap_adjust_read_range() assumes that the position and length passed in are block-aligned. This is not always the case however, as shown in the syzbot generated case for erofs. This causes too many bytes to be skipped for uptodate blocks, which results in returning the incorrect position and length to read in. If all the blocks are uptodate, this underflows length and returns a position beyond the folio.
Fix the calculation to also take into account the block offset when calculating how many bytes can be skipped for uptodate blocks.
Weakness: CWE-190
Which versions are affected by CVE-2025-68794?
How do I fix CVE-2025-68794?
Apply the vendor's patch.
Is CVE-2025-68794 being exploited?
There is no known exploitation of CVE-2025-68794 in the wild and no public exploit code.
Sources
Also known as AZL-74483, BELL-CVE-2025-68794, DEBIAN-CVE-2025-68794, GHSA-3c24-c79w-qw24, ROOT-OS-DEBIAN-11-CVE-2025-68794, ROOT-OS-DEBIAN-12-CVE-2025-68794 and 3 more.