# CVE-2026-97043: Go cgo LDFLAGS validation bypass in cmd/cgo

Source: https://junglewise.ai/threats/cve-2026-97043-building-a-malicious-package-that-uses-cgo-could-bypass-cgo  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-11. Updated: 2026-11-11  
License: CC BY 4.0 with a link back

CVE-2026-97043 · Severity: info · Published 2026-11-11

Go's cgo tool is used to build packages that mix Go and C code. A malicious package could bypass Go's security checks on linker flags, allowing arbitrary code to run during the build process or causing the build to crash.

Technologies: [toolchain (Go)](https://junglewise.ai/threats/technologies/toolchain). Vendors: [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-97043 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-97043 being exploited in the wild.

**How severe is CVE-2026-97043?** Informational severity, published 11 November 2026.

**Which products and versions are affected?** toolchain (Go) SEMVER:introduced=0,fixed=1.26.11,introduced=1.27.0-0,fixed=1.27.4.

**Is there a fix for CVE-2026-97043?** Yes. toolchain (Go): upgrade to 1.27.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-97043 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-97043?** Check whether you run cgo (Go) or toolchain (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- toolchain (Go): upgrade to 1.27.4 or later

  ```sh
  go get toolchain@v1.27.4
  ```


## Technical details

The vulnerability exists in cmd/cgo's handling of "#cgo LDFLAGS" directives. When cmd/cgo generates "_cgo_gotypes.go", it quotes arguments with strconv.Quote in "//go:cgo_ldflag" directives, but cmd/compile and cmd/go parsed these directives by splitting on raw quote characters without properly unquoting the string, allowing attackers to smuggle disallowed linker flags past validation. Additionally, deduplicating LDFLAGS could panic with an out-of-bounds slice index. The fix involves proper handling of backslash-escaped quotes and correct unquoting using strconv.Unquote.

## Affected products

- Go cgo

## Identifiers

- CVE-2026-97043
- GO-2026-6848

## Timeline

- 2026-11-11: disclosed

## References

- [https://pkg.go.dev/](https://pkg.go.dev/)
- [https://go.dev/cl/862156](https://go.dev/cl/862156)

## Related threats

- [Go compiler unsafe library path validation in Windows linker](https://junglewise.ai/threats/cve-2026-97042-building-a-malicious-package-that-uses-go-cgo-import-dynamic-or)
- [Go compiler cgo linker flag injection via directives](https://junglewise.ai/threats/cve-2026-97041-building-a-malicious-package-containing-go-cgo-compiler)
- [Go linker arbitrary flag injection via crafted .syso files](https://junglewise.ai/threats/cve-2026-97040-building-a-package-containing-a-crafted-syso-file-could-bypass)
- [Go command unsafe pkg-config flag handling in cgo](https://junglewise.ai/threats/cve-2026-97039-building-a-malicious-package-that-uses-cgo-pkg-config-directives)
- [Go linker code injection via malicious package compilation](https://junglewise.ai/threats/cve-2026-97038-building-a-malicious-package-containing-syso-files-or-cgo-linker)