Description
Starting from Rust 1.87.0 and before Rust 1.89.0, the tier 3 Cygwin target (`x86_64-pc-cygwin`) didn't correctly handle path separators, causing the standard library's Path API to ignore path components separated by backslashes. Due to this, programs compiled for Cygwin that validate paths could misbehave, potentially allowing path traversal attacks or malicious filesystem operations.
Rust 1.89.0 fixes the issue by handling both Win32 and Unix style paths in the standard library for the Cygwin target.
While we assess the severity of this vulnerability as "medium", please note that the tier 3 Cygwin compilation target is only available when building it from source: no pre-built binaries are distributed by the Rust project, and it cannot be installed through Rustup. Unless you manually compiled the `x86_64-pc-cygwin` target you are not affected by this vulnerability. Users of the tier 1 MinGW target (`x86_64-pc-windows-gnu`) are also explicitly not affected.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Rust Project | std | 1.87.0 – < 1.89.0 | 1.89.0 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | rustc | 1.89.0+dfsg1-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 25.10 | rustc-1.88 | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Hardened Images 1 | rust +18 | 1.97.1-2.hum1 | RHSA-2026:45341 |
Advisories 2
- RHSA-2026:45341 Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update Red Hat Security Advisories (RHSA) · Oct 16, 2026
- WID-SEC-2026-1226 Red Hat Hardened Images RPMs: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 14, 2026