---
id: CVE-2026-55785
title: free5GC is an open-source implementation of the 5G core network
summary: >-
  free5GC is an open-source implementation of the 5G core network. Prior to
  1.4.5, the AUSF component performs cryptographic authentication comparisons in
  internal/sbi/processor/ue_authentication.go with ordinary equality helpers.
  Auth5gAk…
severity: low
cvss: 3.7
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N'
cwe:
  - CWE-208
  - CWE-385
  - CWE-532
vendor: free5gc
product: github.com/free5gc/ausf
affected:
  - github.com/free5gc/ausf < 1.4.5
patched:
  - github.com/free5gc/ausf 1.4.5
published: '2026-08-28'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T21:11:31.703'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-55785'
references:
  - url: >-
      https://github.com/free5gc/ausf/commit/7a5a4aa1ec6cd0e1febebf333911c3104968edf0
    label: security-advisories@github.com
  - url: 'https://github.com/free5gc/ausf/pull/63'
    label: security-advisories@github.com
  - url: 'https://github.com/free5gc/ausf/releases/tag/v1.4.5'
    label: security-advisories@github.com
  - url: 'https://github.com/free5gc/free5gc/security/advisories/GHSA-fp46-6vfw-gc9c'
    label: security-advisories@github.com
  - url: 'https://github.com/advisories/GHSA-fp46-6vfw-gc9c'
tags:
  - nvd
  - ghsa
  - go
epss: 0.00445
epssPercentile: 0.36072
aliases:
  - GHSA-fp46-6vfw-gc9c
ecosystem: go
ingestedAt: '2026-08-28T23:26:57.556Z'
---

## Overview

free5GC is an open-source implementation of the 5G core network. Prior to 1.4.5, the AUSF component performs cryptographic authentication comparisons in internal/sbi/processor/ue_authentication.go with ordinary equality helpers. Auth5gAkaComfirmRequestProcedure compares RES* and XRES* with strings.EqualFold and logs the expected XRES* value at INFO level before comparison. EapAuthComfirmRequestProcedure compares AT_MAC and XMAC with bytes.Equal and evaluates XRES == RES with ordinary string equality. These comparisons can return at mismatch-dependent times, although testing did not demonstrate a practical remote timing oracle because of HTTP/SBI timing noise. The INFO log exposes authentication material to operators, log collectors, sidecars, or processes able to read AUSF logs. This issue is fixed in version 1.4.5.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-55785)

Affected packages:

- `github.com/free5gc/ausf < 1.4.5`

Patched in:

- `github.com/free5gc/ausf 1.4.5`

Source: https://github.com/advisories/GHSA-fp46-6vfw-gc9c