{"id":"CVE-2026-55785","state":"PUBLISHED","title":"free5GC AUSF uses non-constant-time authentication comparisons and logs XRES* in 5G-AKA","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.","publishedAt":"2026-08-28T22:25:06.814Z","updatedAt":"2026-08-31T18:53:29.062Z","severity":{"score":3.7,"label":"Low","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["free5gc free5gc"],"affected":[{"vendor":"free5gc","product":"free5gc","versions":[{"version":"< 1.4.5","status":"affected"}]}],"references":["https://github.com/free5gc/free5gc/security/advisories/GHSA-fp46-6vfw-gc9c","https://github.com/free5gc/ausf/pull/63","https://github.com/free5gc/ausf/commit/7a5a4aa1ec6cd0e1febebf333911c3104968edf0","https://github.com/free5gc/ausf/releases/tag/v1.4.5"],"weaknesses":["CWE-208","CWE-385","CWE-532"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/55xxx/CVE-2026-55785.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-55785","state":"PUBLISHED","datePublished":"2026-08-28T22:25:06.814Z","dateUpdated":"2026-08-31T18:53:29.062Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-17T14:40:28.380Z"},"containers":{"cna":{"title":"free5GC AUSF uses non-constant-time authentication comparisons and logs XRES* in 5G-AKA","descriptions":[{"lang":"en","value":"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":[{"vendor":"free5gc","product":"free5gc","versions":[{"version":"< 1.4.5","status":"affected"}]}],"references":[{"url":"https://github.com/free5gc/free5gc/security/advisories/GHSA-fp46-6vfw-gc9c","name":"https://github.com/free5gc/free5gc/security/advisories/GHSA-fp46-6vfw-gc9c","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/free5gc/ausf/pull/63","name":"https://github.com/free5gc/ausf/pull/63","tags":["x_refsource_MISC"]},{"url":"https://github.com/free5gc/ausf/commit/7a5a4aa1ec6cd0e1febebf333911c3104968edf0","name":"https://github.com/free5gc/ausf/commit/7a5a4aa1ec6cd0e1febebf333911c3104968edf0","tags":["x_refsource_MISC"]},{"url":"https://github.com/free5gc/ausf/releases/tag/v1.4.5","name":"https://github.com/free5gc/ausf/releases/tag/v1.4.5","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":3.7,"baseSeverity":"LOW","confidentialityImpact":"LOW","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-208","lang":"en","description":"CWE-208: Observable Timing Discrepancy","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-385","lang":"en","description":"CWE-385: Covert Timing Channel","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-532","lang":"en","description":"CWE-532: Insertion of Sensitive Information into Log File","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-08-28T22:25:06.814Z"},"source":{"advisory":"GHSA-fp46-6vfw-gc9c","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-31T15:21:05.453756Z","id":"CVE-2026-55785","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-31T18:53:29.062Z"}}]}}}