CVE-2026-80560
In the Linux kernel, the following vulnerability has been resolved: openrisc: signal: do not restore privileged SR bits on sigreturn restore_sigcontext() copies the whole supervision register (SR) from the signal frame and only clears SPR_SR_SM before…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.13%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
In the Linux kernel, the following vulnerability has been resolved: openrisc: signal: do not restore privileged SR bits on sigreturn restore_sigcontext() copies the whole supervision register (SR) from the signal frame and only clears SPR_SR_SM before the value is reloaded into the hardware SR (through ESR and l.rfe) on the return to user space. All other SR bits are left under user control. An unprivileged task can thus return from a signal handler through a crafted sigframe that clears SPR_SR_DME. With the data MMU disabled the CPU performs no translation or protection on data accesses, so the task gains read and write access to arbitrary physical memory, a local privilege escalation. SPR_SR_IME, SPR_SR_SUMRA, SPR_SR_LEE, SPR_SR_EPH and the cache-enable bits are exposed the same way. The ptrace GPR regset already refuses any change to SR for exactly this reason. Restore only the arithmetic flag bits (F, CY, OV) from the signal frame and take every privileged control bit from the SR the kernel saved on signal entry. Verified with qemu-system-or1k -M or1k-sim: before this change an unprivileged PoC clears SPR_SR_DME in rt_sigreturn and writes a marker to physical address 0x03000000 (beyond the kernel's mem=32M); afterwards the same PoC receives SIGSEGV and physical memory is unchanged.
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.13% probability · 3th percentile
- CISA KEV
- Not listed
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/212fc482ddd7f9ccdd74a05eab1cac849350dcd6
- https://git.kernel.org/stable/c/32ef1b30ad736519f7a207bcc2986f3d4129d972
- https://git.kernel.org/stable/c/89a91b30685c0493b0fa2b47d0ab41061a63069d
- https://git.kernel.org/stable/c/a88d688be8d7f03cbf927f2ab454ea9fa58d2979
- https://git.kernel.org/stable/c/b4d73c3848bae9084fa8b9b2aa76d99a7d8eb17d
- https://git.kernel.org/stable/c/bc2e24ba6e167ccf374a197457aa5640a802f429
- https://git.kernel.org/stable/c/cd8b43a71755c516f5c1f265a103438ae9ab15be
- https://git.kernel.org/stable/c/cf1b5514ddf9df098ce7e3741fc9679fd85a4ec6
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.