CVE-2026-97035VulnerabilityPublished 11 Nov 2026

When using Clang or GCC, building a malicious package that uses cgo could cause unexpected code execution at build

Source GCVE Database

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Authoritative record:CVE-2026-97035· High

Not known to be exploited : upgrade to 1.27.4 or 1.26.11 soon.

Data as of 11 Nov 2026, 08:03 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

Thin evidence

One scorer or none

Patch: Available – fixed in 1.27.4, 1.26.11

Exploitation evidence

Disclosed: evidence found.
CVE published 11 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-6f8j-v7cw-qxpp

What to do

Upgrade cmd/go to 1.27.4 or 1.26.11.

Affected software

Product	Affected	Fixed in
Go toolchaincmd/go	Affected >=1.27.0-0 <1.27.4	Fixed in 1.27.4
Go toolchaincmd/go	Affected <1.26.11	Fixed in 1.26.11
Gocmd/go`pkg:golang/cmd/go`Other threats	Affected <1.26.11 >=1.27.0-0 <1.27.4	Fixed in 1.26.11 1.27.4

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

The vendor has disallowed the use of -gen-* and -gnat* flags in #cgo compiler and linker flags to prevent exploitation. Users should ensure they are using versions of the Go toolchain that include this restriction.

Description

A vulnerability exists in the use of Clang or GCC compilers when building malicious Go packages that use cgo. Malicious packages can exploit certain compiler and linker flags (-gen-* and -gnat*) in #cgo directives to cause unexpected code execution during build or write files to arbitrary directories. These flags were previously allowed due to wildcard matching in the allowlists, enabling attackers to write compilation database fragments and sidecar output files outside intended locations and to desynchronize flag argument parsing, potentially passing unvalidated inputs to the linker. The problematic flags are now disallowed in #cgo compiler and linker flags to mitigate this issue.

Impact

The vulnerability allows a malicious Go package using cgo to execute unexpected code during the build process or write files to arbitrary directories on the build system. This can lead to unauthorized file creation or modification and potential compromise of the build environment. However, there is no indication of active exploitation in the wild at this time.

Summary

When building Go packages that use cgo with Clang or GCC, malicious packages could exploit the previously allowed use of compiler and linker flags matching the -g* wildcard, specifically Clang's -gen-cdb-fragment-path <dir> and GCC's -gnatO <file> flags. These flags allowed writing files to arbitrary directories and caused desynchronization in flag argument parsing between the go command and the compiler driver, enabling unexpected code execution at build time or unauthorized file writes. The vulnerability arises from the mismatch in flag parsing and the broad wildcard allowlist. The fix involves disallowing the -gen-* and -gnat* flags in #cgo directives to prevent exploitation.

References

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