CVE-2026-97040
Cgo directive injection via .syso files disguised as Go object files in cmd/go and cmd/link
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 "cgo_ldflag" or "cgo_dynamic_linker") 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.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| cmd/go Go toolchain cmd/go
https://pkg.go.dev |
≥ 0; < 1.26.11 (affected, semver) ≥ 1.27.0-0; < 1.27.4 (affected, semver) Other versions: unaffected |
CNA: Go |
| cmd/link Go toolchain cmd/link
https://pkg.go.dev |
≥ 0; < 1.26.11 (affected, semver) ≥ 1.27.0-0; < 1.27.4 (affected, semver) Other versions: unaffected |
CNA: Go |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
No CVSS assessment reported. An unscored record is not a low-severity determination.
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
For agents and automation
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