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High, CVSS 7.5

github.com/ulikunitz/xz fixes readUvarint Denial of Service (DoS)

CVE-2021-29482GHSA-25xm-hr59-7c27

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (github.com/ulikunitz/xz 0.5.8), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
  • CVE-2021-29482: 1.44% estimated exploitation activity in the next 30 days; percentile 73.18 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Impact xz is a compression and decompression library focusing on the xz format completely written in Go. The function readUvarint used to read the xz container format may not terminate a loop provide malicous input. Patches The problem has been fixed in release v0.5.8. Workarounds Limit the size of the compressed file input to a reasonable size for your use case. References The standard library had recently the same issue and got the CVE-2020-16845 allocated. For more information If you have any questions or comments about this advisory: Open an issue in xz.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-25xm-hr59-7c27

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2021-29482

Advisory: github.com/ulikunitz/xz fixes readUvarint Denial of Service (DoS)
IDs: CVE-2021-29482, GHSA-25xm-hr59-7c27
Record: https://patchnext.com/advisories/cve-2021-29482 (revision 1, source checked 26 Oct 2026, 15:04 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/ulikunitz/xz 0.5.8. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/ulikunitz/xz: affected < 0.5.8; fixed in 0.5.8

## Suggested inspection (read-only)
- Go github.com/ulikunitz/xz: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/ulikunitz/xz.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-25xm-hr59-7c27 (GitHub-reviewed advisory GHSA-25xm-hr59-7c27 lists affected ranges: Go github.com/ulikunitz/xz >=0 <0.5.8)

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