CVE-2026-64298

In the Linux kernel, the following vulnerability has been resolved: NFSv4: include MAY_WRITE in open permission mask for O_TRUNC POSIX requires write permission to truncate a file, so an open() that specifies O_TRUNC must be authorized for write access regardless of the O_ACCMODE access mode. nfs_open_permission_mask() builds the access mask passed to nfs_may_open(), which is the local authorization gate for OPENs the client serves itself from a cached write delegation via the can_open_delegated() path in nfs4_try_open_cached(). The mask is derived from O_ACCMODE alone, so an open(O_RDONLY | O_TRUNC) against a file the caller cannot write requests only MAY_READ and passes the local check. The OPEN is then satisfied locally and the truncation is issued to the server as a SETATTR(size=0) over the delegation stateid, which the server accepts under standard write-delegation semantics. POSIX requires that this open fail with EACCES. Include MAY_WRITE in the mask whenever O_TRUNC is set so the local check matches the access the server would have enforced.

• linux linux kernel (>= 2.6.24 < 5.10.261) • linux linux kernel (>= 5.11 < 5.15.212) • linux linux kernel (>= 5.16 < 6.1.178) • linux linux kernel (>= 6.2 < 6.6.145) • linux linux kernel (>= 6.7 < 6.12.96) • linux linux kernel (>= 6.13 < 6.18.39) • linux linux kernel (>= 6.19 < 7.1.4) • linux linux kernel 7.2