{"items":[{"id":"NVI-00012109","kind":"vulnerability","title":"Slack Morphism verifier errors disclose valid HMACs in the logs","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-26w4-8w32-4x3v","CVE-2026-113799"],"plain_summary":"GitHub lists this reviewed advisory for slack-morphism. 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-a923e9457232433596398ff0daae019c"],"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":"2026-10-21T16:38:48.000Z","value":"5.3 medium","meaning":"GitHub source severity; exploitability and local consequence require separate evidence.","source_id":"sr-a923e9457232433596398ff0daae019c"}],"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-a923e9457232433596398ff0daae019c","url":"https://github.com/advisories/GHSA-26w4-8w32-4x3v","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-26w4-8w32-4x3v","publisher":"GitHub Advisory Database","observed_at":"2026-10-31T23:13:39.183Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-a923e9457232433596398ff0daae019c"],"technology":"slack-morphism","known_exclusions":[],"conditions_summary":"### Summary\n\nSlack Morphism exposes the correct Slack request HMAC when signature verification fails.\n\nFor an invalid request, `slack-morphism` computes the correct signature for the attacker-controlled timestamp and request body and stores it in `SlackEventWrongSignatureError.generated_hash`. The error's `Debug` and `Display` representations expose that value, and the default Axum listener error handler logs it at error level.\n\nAn attacker who can both reach the application's Slack callback endpoint and read its application/service logs can therefore use the verifier as a chosen-message HMAC oracle. The attacker can send an arbitrary request with an invalid signature, recover the correct signature from the resulting log entry, and resend the same request within the five-minute freshness window. The second request passes Slack Morphism's signature verification and reaches the protected application callback without the attacker knowing the Slack signing secret.\n\nI reproduced this end-to-end against both the Axum and Hyper integrations in `slack-morphism` 2.26.0 and 2.27.0.\n\n### Details\n\nThe vulnerability is in Slack Morphism's request signature verification error path.\n\nIn `src/sign","public_affected_ranges":[">= 1.0.0, <= 2.27.0"]}],"null_published_at":"2026-11-01T01:03:56.631Z","source_updated_at":"2026-10-21T16:38:48.000Z","source_disclosed_at":"2026-10-21T16:38:47.000Z","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":"2026-10-31T23:13:39.183Z"}],"next_cursor":null,"snapshot_revision":"42594"}