# CVE-2026-97039: Flag sanitization bypass via "#cgo pkg-config:" directives in cmd/go

Status: published. Published: 2026-11-11. Updated: 2026-11-11.

Building a malicious package that uses "#cgo pkg-config:" directives could load untrusted pkg-config ".pc" files or inject unvalidated compiler and linker flags. The pkg-config flag allowlist previously permitted "--with-path=" and "--personality=", allowed "--define-variable=" values beginning with "=" or "$" (which can rewrite paths in system ".pc" files into sysroot-prefixed "-L=" or "-L$SYSROOT" linker search paths), and allowed package arguments ending in ".pc" or containing path separators or "..", which caused pkg-config to load local ".pc" files directly from the package directory. In addition, flags returned by "pkg-config --cflags" in cgoCPPFLAGS were not checked when determining whether internal linking is safe. The go command now disallows "--with-path=", "--personality=", leading "=" or "$" characters in "--define-variable=" values, and local ".pc" paths in "#cgo pkg-config:" directives, and inspects cgoCPPFLAGS when checking internal linking compatibility.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Go toolchain / cmd/go (cmd/go): ≥ 0; < 1.26.11 (affected, semver); ≥ 1.27.0-0; < 1.27.4 (affected, semver). Source: CNA: Go

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-88

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://go.dev/cl/862152 (CNA: Go)

- https://go.dev/issue/82571 (CNA: Go)

- https://groups.google.com/g/golang-announce/c/iY8TY0wWgbM (CNA: Go)

- https://pkg.go.dev/vuln/GO-2026-6852 (CNA: Go)

## Provenance

- CNA: Go: https://www.cve.org/CVERecord?id=CVE-2026-97039; retrieved 2026-11-11; source updated 2026-11-11

Revision: 754666ab6b3a75ab64d78b1ecc0f46e2dfe3a53fa51538608c053d0c0187eb58

Canonical: https://y2.dev/cve/CVE-2026-97039

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