{"items":[{"id":"NVI-00013788","kind":"vulnerability","title":"free5GC AUSF uses non-constant-time authentication comparisons and logs XRES* in 5G-AKA","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-fp46-6vfw-gc9c","CVE-2026-55785"],"plain_summary":"GitHub lists this reviewed advisory for github.com/free5gc/ausf. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.","review_status":"source_listed","control_topics":[],"public_actions":[{"summary":"Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.","source_ids":["sr-04374fbf66a6a23bbf1b073aff59bb96"],"action_type":"investigate","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null}],"schema_version":"1.1.0","source_metrics":[{"kind":"CVSS","as_of":"2026-08-28T22:26:16.000Z","value":"3.7 low","meaning":"GitHub source severity; exploitability and local consequence require separate evidence.","source_id":"sr-04374fbf66a6a23bbf1b073aff59bb96"}],"why_it_matters":"Published affected context helps an owner decide what evidence to gather. This report has not examined your application.","related_sources":[{"id":"sr-04374fbf66a6a23bbf1b073aff59bb96","url":"https://github.com/advisories/GHSA-fp46-6vfw-gc9c","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-fp46-6vfw-gc9c","publisher":"GitHub Advisory Database","observed_at":"2026-11-02T02:21:58.521Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-04374fbf66a6a23bbf1b073aff59bb96"],"technology":"github.com/free5gc/ausf","known_exclusions":[],"conditions_summary":"### Summary\n\nThe AUSF component of free5GC compares authentication response values with normal Go equality helpers instead of constant-time cryptographic comparison functions.\n\nTwo authentication flows are affected in `internal/sbi/processor/ue_authentication.go`:\n\n1. 5G-AKA confirmation compares `RES*` and `XRES*` with `strings.EqualFold()`.\n2. EAP-AKA' confirmation compares `AT_MAC` with `bytes.Equal()` and compares `XRES` and `RES` with `==`.\n\nThese functions are not designed to be constant-time cryptographic comparators and may return earlier depending on the location of the first mismatch.\n\nAdditionally, the 5G-AKA confirmation path logs both the received `res*` and the expected `Xres*` at INFO level immediately before comparing them. The `XRES*` value is authentication material and should not be written to application logs.\n\nThe timing side channel was confirmed as a code issue, but practical exploitation over HTTP was not demonstrated in the lab because the comparator-level signal is much smaller than HTTP/SBI noise. The `XRES*` logging issue is directly observable in AUSF logs.\n\nConfirmed on `github.com/free5gc/ausf` v1.4.4 and current main as of the May 2026 analysis.\n\n###","public_affected_ranges":["< 1.4.5"]}],"null_published_at":"2026-11-02T10:00:37.149Z","source_updated_at":"2026-08-28T22:26:16.000Z","source_disclosed_at":"2026-08-28T22:26:16.000Z","is_synthetic_fixture":false,"null_last_reviewed_at":null,"public_change_summary":"First indexed by Null; source disclosure date is shown separately.","null_first_observed_at":"2026-11-02T02:21:58.521Z"}],"next_cursor":null,"snapshot_revision":"42594"}