{"id":"CVE-2026-80560","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-80560","summary":"openrisc: signal: do not restore privileged SR bits on sigreturn","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nopenrisc: signal: do not restore privileged SR bits on sigreturn\n\nrestore_sigcontext() copies the whole supervision register (SR) from the\nsignal frame and only clears SPR_SR_SM before the value is reloaded into\nthe hardware SR (through ESR and l.rfe) on the return to user space.  All\nother SR bits are left under user control.\n\nAn unprivileged task can thus return from a signal handler through a\ncrafted sigframe that clears SPR_SR_DME.  With the data MMU disabled the\nCPU performs no translation or protection on data accesses, so the task\ngains read and write access to arbitrary physical memory, a local\nprivilege escalation.  SPR_SR_IME, SPR_SR_SUMRA, SPR_SR_LEE, SPR_SR_EPH\nand the cache-enable bits are exposed the same way.  The ptrace GPR regset\nalready refuses any change to SR for exactly this reason.\n\nRestore only the arithmetic flag bits (F, CY, OV) from the signal frame\nand take every privileged control bit from the SR the kernel saved on\nsignal entry.\n\nVerified with qemu-system-or1k -M or1k-sim: before this change an\nunprivileged PoC clears SPR_SR_DME in rt_sigreturn and writes a marker to\nphysical address 0x03000000 (beyond the kernel's mem=32M); afterwards the\nsame PoC receives SIGSEGV and physical memory is unchanged.","published":"2026-08-26T14:37:25.971Z","modified":"2026-08-28T03:47:29.097188673Z","cvss":{"score":7.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"5.10.266"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/212fc482ddd7f9ccdd74a05eab1cac849350dcd6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/32ef1b30ad736519f7a207bcc2986f3d4129d972"},{"type":"WEB","url":"https://git.kernel.org/stable/c/89a91b30685c0493b0fa2b47d0ab41061a63069d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a88d688be8d7f03cbf927f2ab454ea9fa58d2979"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b4d73c3848bae9084fa8b9b2aa76d99a7d8eb17d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bc2e24ba6e167ccf374a197457aa5640a802f429"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cd8b43a71755c516f5c1f265a103438ae9ab15be"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cf1b5514ddf9df098ce7e3741fc9679fd85a4ec6"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80560.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80560"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-28T03:47:29.097188673Z"}}