ewen-lbh/ffcss Late-Unicode normalization vulnerability

Exploitation

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

CVSS

5.3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS

• CVE-2023-52081: 0.52% estimated exploitation activity in the next 30 days; percentile 44.38 (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.

Summary The function lookupPreprocess() is meant to apply some transformations to a string by disabling characters in the regex [- .]. However, due to the use of late Unicode normalization of type NFKD, it is possible to bypass that validation and re-introduce all the characters in the regex [- .]. Take the following equivalent Unicode character U+2024 (․). Initially, the lookupPreprocess() function would compile the regex and replace the regular dot (.). However, the U+2024 (․) would bypass the ReplaceAllString(). When the normalization operation is applied to U+2024 (․), the resulting character will be U+002E (.). Thus, the dot was reintroduced back. Impact The lookupPreprocess() can be easily bypassed with equivalent Unicode characters like U+FE4D (﹍), which would result in the omitted U+005F (), for instance. It should be noted here that the variable s is user-controlled data coming from /cmd/ffcss/commands.go#L22-L28 the command args. The lookupPreprocess() function is only ever…

Published by the source

28 Dec 2023, 21:16 UTC

Last modified by the source

1 Mar 2024, 14:35 UTC

Source last checked

26 Oct 2026, 15:03 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-wpmx-564x-h2mh

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# Patch Next advisory brief: CVE-2023-52081

Advisory: ewen-lbh/ffcss Late-Unicode normalization vulnerability
IDs: CVE-2023-52081, GHSA-wpmx-564x-h2mh
Record: https://patchnext.com/advisories/cve-2023-52081 (revision 1, source checked 26 Oct 2026, 15:03 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/ewen-lbh/ffcss 0.2.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/ewen-lbh/ffcss: affected < 0.2.0; fixed in 0.2.0

## Suggested inspection (read-only)
- Go github.com/ewen-lbh/ffcss: 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/ewen-lbh/ffcss.
- 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-wpmx-564x-h2mh (GitHub-reviewed advisory GHSA-wpmx-564x-h2mh lists affected ranges: Go github.com/ewen-lbh/ffcss >=0 <0.2.0)

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