ALPINE-CVE-2026-97040: Alpine/go vulnerability
Building a package containing a crafted ".syso" file could bypass cgo flag validation and inject arbitrary linker flags when linking. When loading ".syso" entries from a package archive, the linker only checked for recognized host object headers (ELF, Mach-O, PE, and XCOFF) before falling through to Go object parsing. A ".syso" file beginning with a "go object" header was parsed as a Go compiler object, allowing untrusted cgo metadata directives (such as "cgoldflag" or "cgodynamiclinker") embedded in the ".syso" file to be passed to the external linker without validation. Additionally, ".syso" filenames longer than 16 bytes lost their ".syso" extension when truncated in archive headers, and unrecognized ".syso" formats forced external linking in pure-Go builds. The linker now rejects ".syso" files that are not recognized host object formats, and "cmd/go" and "cmd/pack" preserve the ".syso" suffix when truncating long archive member names.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
alpine/goto a version that resolves this vulnerability.Fixed in 1.26.11-r0
Event History
Frequently Asked Questions
Who is exposed to this issue?
Build environments that compile a package containing an untrusted or crafted .syso file are exposed. The crafted file can carry cgo metadata that reaches the external linker.
What does an attacker need to exploit it?
An attacker needs to get a crafted .syso file included in a package being built. The file must begin with a Go object header so it is parsed as a Go compiler object rather than rejected as an unrecognized host object.
Are pure-Go builds affected?
Yes. An unrecognized .syso format could force external linking even in pure-Go builds, which may make the unsafe linker-flag path relevant.
How can teams reduce risk before updating?
Do not build packages containing untrusted .syso files, and review package contents for .syso members before building. Treat .syso files with unexpected formats or embedded cgo metadata directives as unsafe.
How can I identify potentially affected build inputs?
Inspect package archives and source trees for .syso files, including names longer than 16 bytes that may be truncated in archive headers. Pay particular attention to .syso content beginning with a Go object header or containing cgo_ldflag or cgo_dynamic_linker directives.