# CVE-2026-80560: openrisc: signal: do not restore privileged SR bits on sigreturn

CVE-2026-80560 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-80560, released August 27, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-80560
- Priority: High
- CVSS: 7.8 (Important)
- EPSS: 0.0013
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 26, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-80560

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 6.1.187-1 | [DEBIAN-CVE-2026-80560](https://patchblox.com/security/data/fix/linux/debian-cve-2026-80560.md) | Aug 27, 2026 |
| Linux | linux Debian 13.5 (trixie) | 6.12.105-1 | [DEBIAN-CVE-2026-80560](https://patchblox.com/security/data/fix/linux/debian-cve-2026-80560.md) | Aug 27, 2026 |
| Linux | linux Debian 14 | 7.1.10-1 | [DEBIAN-CVE-2026-80560](https://patchblox.com/security/data/fix/linux/debian-cve-2026-80560.md) | Aug 27, 2026 |
| Linux | linux-6.12 Debian 12.15 (bookworm) | 6.12.107-1~deb12u1 | [DEBIAN-CVE-2026-80560](https://patchblox.com/security/data/fix/linux/debian-cve-2026-80560.md) | Aug 27, 2026 |

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Data as of 2026-11-09T01:18:40Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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