Answer in brief
CVE-2026-89793 records a High severity (CVSS 7.8) vulnerability in ublk: clear VM_MAYWRITE on read-only ublk char device mmap. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=71f28f3136aff5890cd56de78abc673f8393cad9 <be41733c24be58e2a1ef718c80fafdfb98a40d5e || >=71f28f3136aff5890cd56de78abc673f8393cad9 <5befd06a72216869b607cf7724a4f16c6a2d3999 || >=71f28f3136aff5890cd56de78abc673f8393cad9 <e373c1acdbcf88cec533ece9f589020adaed0a78 || >=71f28f3136aff5890cd56de78abc673f8393cad9 <fa5e1bc673ca59722608af67b27e65dba0c97926 || >=71f28f3136aff5890cd56de78abc673f8393cad9 <6e2b571b0a54755b06e092501913e1dfefe75d6c | be41733c24be58e2a1ef718c80fafdfb98a40d5e, 5befd06a72216869b607cf7724a4f16c6a2d3999, e373c1acdbcf88cec533ece9f589020adaed0a78, fa5e1bc673ca59722608af67b27e65dba0c97926, 6e2b571b0a54755b06e092501913e1dfefe75d6c |
| Linux/Linuxgeneric | 6.0 | Not reported |
| Linux/Linuxgeneric | >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <be41733c24be58e2a1ef718c80fafdfb98a40d5e || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5befd06a72216869b607cf7724a4f16c6a2d3999 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e373c1acdbcf88cec533ece9f589020adaed0a78 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <fa5e1bc673ca59722608af67b27e65dba0c97926 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6e2b571b0a54755b06e092501913e1dfefe75d6c || >=0 <6.6.157 || >=0 <6.12.110 || >=0 <6.18.51 || >=0 <7.2.5 | be41733c24be58e2a1ef718c80fafdfb98a40d5e, 5befd06a72216869b607cf7724a4f16c6a2d3999, e373c1acdbcf88cec533ece9f589020adaed0a78, fa5e1bc673ca59722608af67b27e65dba0c97926, 6e2b571b0a54755b06e092501913e1dfefe75d6c, 6.6.157, 6.12.110, 6.18.51, 7.2.5 |
Published upstream
Sep 16, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Sep 16, 2026
In the Linux kernel, the following vulnerability has been resolved: ublk: clear VM_MAYWRITE on read-only ublk char device mmap ublk_ch_mmap() rejects mmap requests with VM_WRITE set, but never clears VM_MAYWRITE on the resulting read-only mapping. This allows a userspace daemon to mmap the per-queue command buffer PROT_READ, then upgrade it to PROT_WRITE via mprotect(), since VM_MAYWRITE was never cleared. The command buffer holds struct ublksrv_io_desc entries that are kernel-written ABI; a writable mapping lets an unprivileged daemon process corrupt fields such as addr, op_flags, nr_sectors, and start_sector. Same bug class as the drm/panthor and drm/vc4 VM_MAYWRITE fixes, and the 2026-08-13 ptp/vmclock fix (a5edadbae57e). Verified via mprotect() PoC: before the fix, a PROT_READ mapping can be upgraded to PROT_READ|PROT_WRITE and a write into the command buffer corrupts io_desc fields (confirmed under KASAN). After the fix, mprotect() returns -EACCES.
Quoted source text, attributed separately from HOL analysis.