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CVE-2026-55785— free5GC AUSF uses non-constant-time authentication comparisons and logs XRES* in 5G-AKA

Quick assessment

Affected
free5gc free5gc
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

free5GC是free5GC团队开源的一个第 5 代 (5G) 移动核心网络的项目平台。 free5GC 1.4.5之前版本存在安全漏洞，该漏洞源于AUSF组件在加密认证比较时使用普通相等辅助函数，并在比较前将预期XRES*值记录到INFO日志，可能导致认证材料泄露给能够读取AUSF日志的操作者或进程。

CVSS 3.7 · Low EPSS 0.45% · P37

Affected Version Matrix 1

VendorProduct Version RangeStatus
free5gc free5gc < 1.4.5 affected
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I. Basic Information for CVE-2026-55785

Vulnerability Information
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Vulnerability Title
free5GC AUSF uses non-constant-time authentication comparisons and logs XRES* in 5G-AKA
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
通过时间差异性导致的信息暴露
Source: CVE Program / CVE List V5
Vulnerability Title
free5GC 侧信道信息泄露漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
free5GC是free5GC团队开源的一个第 5 代 (5G) 移动核心网络的项目平台。 free5GC 1.4.5之前版本存在安全漏洞，该漏洞源于AUSF组件在加密认证比较时使用普通相等辅助函数，并在比较前将预期XRES*值记录到INFO日志，可能导致认证材料泄露给能够读取AUSF日志的操作者或进程。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
free5gc free5gc < 1.4.5 -

II. Public POCs for CVE-2026-55785

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III. Intelligence Information for CVE-2026-55785

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Patches & Fixes for CVE-2026-55785 (2)

Vendor Advisories for CVE-2026-55785 (1)

Vendor Pages for CVE-2026-55785 (1)

Same Patch Batch · free5gc · 2026-08-28 · 3 CVEs total

CVE-2026-55068 9.3 CRITICAL free5GC: NRF nnrf-nfm lacks NF Profile input validation — enables NF Registration Poisonin
CVE-2026-55784 7.5 HIGH free5GC AUSF authentication contexts can be overwritten by concurrent requests for the sam

IV. Related Vulnerabilities

Same product: free5gc
Same vendor: free5gc
Same weakness: CWE-208

V. Comments for CVE-2026-55785

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