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Unrated

Add recursion depth guard during decode in encoding/xml

CVE-2026-56859

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (stdlib 1.27.0-rc.3, 1.26.6, 1.25.13), 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

  • Go stdlib

    Affected
    < 1.25.13>= 1.26.0-0, < 1.26.6>= 1.27.0-0, < 1.27.0-rc.3
    Fixed in
    1.25.13, 1.26.6, 1.27.0-rc.3

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
not scored
EPSS
  • CVE-2026-56859: 0.57% estimated exploitation activity in the next 30 days; percentile 47.11 (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.

Previously, DecodeElement would reset the depth counter causing it to never fire; this could lead to stack exhaustion.

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

    Published from osv record GO-2026-6088

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-2026-56859

Advisory: Add recursion depth guard during decode in encoding/xml
IDs: CVE-2026-56859
Record: https://patchnext.com/advisories/cve-2026-56859 (revision 1, source checked 23 Oct 2026, 22:04 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: stdlib 1.27.0-rc.3, 1.26.6, 1.25.13. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go stdlib: affected < 1.25.13; >= 1.26.0-0, < 1.26.6; >= 1.27.0-0, < 1.27.0-rc.3; fixed in 1.25.13, 1.26.6, 1.27.0-rc.3

## Suggested inspection (read-only)
- Go stdlib: 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 stdlib.
- 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://osv.dev/vulnerability/GO-2026-6088 (OSV record GO-2026-6088 lists affected ranges: Go stdlib >=0 =1.26.0-0 =1.27.0-0 <1.27.0-rc.3 (fixed))

Commands are suggestions: review each one before running it.

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