RandomAlphaNumeric and CryptoRandomAlphaNumeric are not as random as they should be

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

not scored

EPSS

• CVE-2021-4238: 1.41% estimated exploitation activity in the next 30 days; percentile 72.65 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact A security-sensitive bug was discovered by Open Source Developer Erik Sundell of Sundell Open Source Consulting AB. The functions RandomAlphaNumeric(int) and CryptoRandomAlphaNumeric(int) are not as random as they should be. Small values of int in the functions above will return a smaller subset of results than they should. For example, RandomAlphaNumeric(1) will always return a digit in the 0-9 range, while RandomAlphaNumeric(4) will return around ~7 million of the ~13M possible permutations. This is considered a security release because programs that rely upon random generators for passwords are at an increased risk of brute force-style password guessing. There is also a higher probability of collision. The problem was the result of a mistaken regular expression that only accepted random strings if they contained a digit from [0-9]. That restriction has been removed. Patches This issue has been corrected in v1.1.1. Workarounds If you cannot upgrade to v1.1.1, you can work…

Published by the source

21 May 2021, 16:26 UTC

Last modified by the source

23 Jan 2026, 22:52 UTC

Source last checked

26 Oct 2026, 15:14 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-xg2h-wx96-xgxr

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# Patch Next advisory brief: CVE-2021-4238

Advisory: RandomAlphaNumeric and CryptoRandomAlphaNumeric are not as random as they should be
IDs: CVE-2021-4238, GHSA-xg2h-wx96-xgxr
Record: https://patchnext.com/advisories/cve-2021-4238 (revision 1, source checked 26 Oct 2026, 15:14 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: github.com/Masterminds/goutils 1.1.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/Masterminds/goutils: affected < 1.1.1; fixed in 1.1.1

## Suggested inspection (read-only)
- Go github.com/Masterminds/goutils: 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/Masterminds/goutils.
- 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-xg2h-wx96-xgxr (GitHub-reviewed advisory GHSA-xg2h-wx96-xgxr lists affected ranges: Go github.com/Masterminds/goutils >=0 <1.1.1)

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