What’s Vulnerable › Vulnerabilities

CVE-2026-89458: s390/dasd: Do not complete a failed ESE read as successful

• Severity: unknown
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-11 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: s390/dasd: Do not complete a failed ESE read as successful dasd_int_handler() completes an NRF read of an unallocated ESE track by calling ese_read() and unconditionally marking the request DASD_CQR_SUCCESS. dasd_eckd_ese_read() can return an error before it has zeroed the destination buffer: a failed sense-data parse or a current track outside the requested range both return early, leaving the destination pages untouched. The request is still completed successfully, so the block layer is handed stale / uninitialized memory instead of zeros. Check the ese_read() return value and fail the request through the normal error path instead of forcing DASD_CQR_SUCCESS.

Affected products

• Linux kernel: from 5.4.26 before 5.5; from 5.5.10 before 5.6; 5.6 — fixed in 5.5, 5.6, 7.3

How to fix

Upgrade to a fixed version: Linux kernel 5.5, 5.6, 7.3. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/52b331c99baac653ca794bd8487c8ec4de8db203
• https://git.kernel.org/stable/c/55f4df40178cdfede0d7ae848fbab00efa9b95c1
• https://git.kernel.org/stable/c/77168af195d04b34c6de62b874624e74d64cef8d
• https://git.kernel.org/stable/c/8cb96cffceead3cbd0541154d7ecc5e6474edda1
• https://git.kernel.org/stable/c/921ff697bb6f7067059793becf8b2d00de71ce41
• https://git.kernel.org/stable/c/b0d94dd6e82df396e2254c8b0f25eff7d19c2e7f
• https://git.kernel.org/stable/c/c9adf8399732306dfc97b3adb4778038743e3f5e
• https://git.kernel.org/stable/c/cddb447c62466f3076938ce120028d7b591f9f37

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