{"document":{"category":"csaf_vex","csaf_version":"2.0","title":"CVE-2026-12151: undici WebSocket client vulnerable to denial of service via fragment count bypass","publisher":{"category":"vendor","name":"HarborGuard Database","namespace":"https://database.harborguard.co"},"tracking":{"id":"CVE-2026-12151","status":"final","version":"1","initial_release_date":"2026-06-17T16:05:38.785Z","current_release_date":"2026-06-17T17:30:13.782Z","revision_history":[{"date":"2026-06-17T16:05:38.785Z","number":"1","summary":"Initial machine-readable export from HarborGuard."}]},"distribution":{"tlp":{"label":"WHITE"},"text":"Public CVE data; freely redistributable."},"notes":[{"category":"description","text":"Impact:\nThe undici WebSocket client enforces maxPayloadSize on the cumulative byte count of fragments in a message but does not enforce a limit on the number of fragments. A malicious WebSocket server can stream many small or empty continuation frames that each pass per-frame and cumulative-size validation, collectively causing unbounded memory growth in the client process. The result is memory exhaustion and a denial of service.\n\nAffected applications are those using the undici WebSocket client (new WebSocket(...)) or the WebSocketStream API that can be induced to connect to an attacker-controlled or compromised WebSocket endpoint.\n\nAll releases starting at undici 6.17.0 are affected.\n\nPatches: Upgrade to undici >= 6.26.0, >= 7.28.0, or >= 8.5.0. Workarounds:\nNo workaround is available. The fix must be applied through an upgrade.","title":"CVE description"}],"references":[{"category":"self","summary":"CVE-2026-12151 on HarborGuard Database","url":"https://database.harborguard.co/cve/CVE-2026-12151"},{"category":"external","summary":"CVE Record","url":"https://www.cve.org/CVERecord?id=CVE-2026-12151"},{"category":"external","summary":"github.com","url":"https://github.com/nodejs/undici/security/advisories/GHSA-vxpw-j846-p89q"},{"category":"external","summary":"cna.openjsf.org","url":"https://cna.openjsf.org/security-advisories.html"}]},"product_tree":{"branches":[{"category":"vendor","name":"undici","branches":[{"category":"product_name","name":"undici","branches":[{"category":"product_version_range","name":"<6.26.0","product":{"name":"undici undici <6.26.0","product_id":"CSAFPID-1","product_identification_helper":{"cpe":"cpe:2.3:a:undici:undici:*:*:*:*:*:*:*:*"}}},{"category":"product_version_range","name":">=7.0.0 <7.28.0","product":{"name":"undici undici >=7.0.0 <7.28.0","product_id":"CSAFPID-2","product_identification_helper":{"cpe":"cpe:2.3:a:undici:undici:*:*:*:*:*:*:*:*"}}},{"category":"product_version_range","name":">=8.0.0 <8.5.0","product":{"name":"undici undici >=8.0.0 <8.5.0","product_id":"CSAFPID-3","product_identification_helper":{"cpe":"cpe:2.3:a:undici:undici:*:*:*:*:*:*:*:*"}}},{"category":"product_version","name":"6.26.0","product":{"name":"undici undici 6.26.0","product_id":"CSAFPID-4","product_identification_helper":{"cpe":"cpe:2.3:a:undici:undici:*:*:*:*:*:*:*:*"}}},{"category":"product_version","name":"7.28.0","product":{"name":"undici undici 7.28.0","product_id":"CSAFPID-5","product_identification_helper":{"cpe":"cpe:2.3:a:undici:undici:*:*:*:*:*:*:*:*"}}},{"category":"product_version","name":"8.5.0","product":{"name":"undici undici 8.5.0","product_id":"CSAFPID-6","product_identification_helper":{"cpe":"cpe:2.3:a:undici:undici:*:*:*:*:*:*:*:*"}}}]}]}]},"vulnerabilities":[{"cve":"CVE-2026-12151","title":"undici WebSocket client vulnerable to denial of service via fragment count bypass","notes":[{"category":"description","text":"Impact:\nThe undici WebSocket client enforces maxPayloadSize on the cumulative byte count of fragments in a message but does not enforce a limit on the number of fragments. A malicious WebSocket server can stream many small or empty continuation frames that each pass per-frame and cumulative-size validation, collectively causing unbounded memory growth in the client process. The result is memory exhaustion and a denial of service.\n\nAffected applications are those using the undici WebSocket client (new WebSocket(...)) or the WebSocketStream API that can be induced to connect to an attacker-controlled or compromised WebSocket endpoint.\n\nAll releases starting at undici 6.17.0 are affected.\n\nPatches: Upgrade to undici >= 6.26.0, >= 7.28.0, or >= 8.5.0. Workarounds:\nNo workaround is available. The fix must be applied through an upgrade.","title":"CVE description"}],"product_status":{"known_affected":["CSAFPID-1","CSAFPID-2","CSAFPID-3"],"fixed":["CSAFPID-4","CSAFPID-5","CSAFPID-6"]},"scores":[{"cvss_v3":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"products":["CSAFPID-1","CSAFPID-2","CSAFPID-3"]}],"remediations":[{"category":"vendor_fix","details":"Update to a fixed version: 6.26.0, 7.28.0, 8.5.0.","product_ids":["CSAFPID-1","CSAFPID-2","CSAFPID-3"]}]}]}