CVE-2026-557853.7LowCWE-208

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

free5gc

Affected: free5gc · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.5%probability of exploitation in the next 30 days

39th percentile

050100

Higher than 39% of scored CVEs

3.7LowCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

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.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

free5gc · free5gc< 1.4.5

On the Atlas

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Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Observable Timing Discrepancy · Information Disclosure
Vendor: free5gc
Published: August 2026
Band: Unlikely (under 1%), August 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-55785 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.