CVE-2026-89793
CVE.org · Published
- Record status
- Published
- Identifier year (not publication year)
- 2026
- Source publication
- Source updated
- Imported by cveboard
- Source snapshot
- cve_2026-10-24_midnight_baseline ·
CNA source text (English)
ublk: clear VM_MAYWRITE on read-only ublk char device mmap
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.
Scoped product and version facts
Fix information unknown; no fixed version is derived here. Missing information does not prove that no fix exists.
Exploitation unknown; this catalogue does not assess exploitation.
Linux
- Vendor
- Linux
- Product
- Linux
- Platforms
- Unknown
- Default status
unaffected
| Version (version) | Status (status) | Version scheme (versionType) | Exclusive end (lessThan) | Inclusive end (lessThanOrEqual) | Status changes (at → status) |
|---|---|---|---|---|---|
| 71f28f3136aff5890cd56de78abc673f8393cad9 | affected | git | be41733c24be58e2a1ef718c80fafdfb98a40d5e | Unavailable | None listed |
| 71f28f3136aff5890cd56de78abc673f8393cad9 | affected | git | 5befd06a72216869b607cf7724a4f16c6a2d3999 | Unavailable | None listed |
| 71f28f3136aff5890cd56de78abc673f8393cad9 | affected | git | e373c1acdbcf88cec533ece9f589020adaed0a78 | Unavailable | None listed |
| 71f28f3136aff5890cd56de78abc673f8393cad9 | affected | git | fa5e1bc673ca59722608af67b27e65dba0c97926 | Unavailable | None listed |
| 71f28f3136aff5890cd56de78abc673f8393cad9 | affected | git | 6e2b571b0a54755b06e092501913e1dfefe75d6c | Unavailable | None listed |
Linux
- Vendor
- Linux
- Product
- Linux
- Platforms
- Unknown
- Default status
affected
| Version (version) | Status (status) | Version scheme (versionType) | Exclusive end (lessThan) | Inclusive end (lessThanOrEqual) | Status changes (at → status) |
|---|---|---|---|---|---|
| 6.0 | affected | Unavailable | Unavailable | Unavailable | None listed |
| 0 | unaffected | semver | 6.0 | Unavailable | None listed |
| 6.6.157 | unaffected | semver | Unavailable | 6.6.* | None listed |
| 6.12.110 | unaffected | semver | Unavailable | 6.12.* | None listed |
| 6.18.51 | unaffected | semver | Unavailable | 6.18.* | None listed |
| 7.2.5 | unaffected | semver | Unavailable | 7.2.* | None listed |
| 7.3 | unaffected | original_commit_for_fix | Unavailable | * | None listed |