CVE-2026-80710 s390/dasd: Fix undersized format-check buffer
An integer overflow in the s390/dasd driver leads to an undersized buffer allocation, allowing out-of-bounds writes and potential privilege escalation.
- 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
What is CVE-2026-80710?
CVE-2026-80710 is a high-severity vulnerability in Linux, published on 28 Aug 2026. 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:
s390/dasd: Fix undersized format-check buffer
fmt_buffer_size in dasd_eckd_check_device_format() is declared as int, even though one of the multiplicands, sizeof(struct eckd_count), is a size_t. The expression
trkcount * rpt_max * sizeof(struct eckd_count)
is therefore correctly evaluated at 64-bit width, but the result is silently truncated when it is stored back into the 32-bit fmt_buffer_size variable. For a sufficiently large track range (start_unit/stop_unit are caller-controlled) this truncation yields a buffer size far smaller than the number of tracks actually requested. kzalloc() then succeeds with an undersized allocation, while the subsequent channel program build still operates on the untruncated track count and writes past the end of that buffer.
Compute the buffer size with check_mul_overflow() and keep it in a size_t, so that a value that no longer fits results in -EINVAL instead of a silently truncated allocation size.
Which versions are affected by CVE-2026-80710?
How do I fix CVE-2026-80710?
Apply the vendor's patch.
Is CVE-2026-80710 being exploited?
There is no known exploitation of CVE-2026-80710 in the wild and no public exploit code.
Sources
Also known as AZL-98193, BELL-CVE-2026-80710, DEBIAN-CVE-2026-80710, GHSA-4j75-ggwr-gg59, UBUNTU-CVE-2026-80710.