{"schema_version":"1.9.0","id":"GHSA-4qv8-2p9j-2685","published":"2026-10-23T22:13:29Z","modified":"2026-10-23T22:30:04.104974737Z","aliases":["CVE-2026-109924"],"summary":"undici vulnerable to Denial of Service via unbounded memory in the EventSource parser","details":"### Impact\n\nundici's `EventSource` client can be driven to exhaust process memory by a malicious or compromised Server-Sent Events peer. By sending millions of tiny completed `data:` fields with no blank event separator, or a single unfinished line split across many chunks, the parser retains a growing amount of per-field and per-chunk state. The byte-based `maxEventSize` and `maxResponseSize` limits do not bound that retained state, and `maxResponseSize` is enforced on the compressed body before decompression, so a small compressed response can expand into enough retained memory to terminate the process. The application only needs to maintain an `EventSource` connection to an untrusted peer, which controls only the response. Availability is the only impact.\n\n### Patches\n\nUpgrade to `6.29.1`, `7.30.1`, or `8.12.2`, which bound the retained EventSource parser state (the number of `data` fields and buffered chunks, the unfinished-line length, and per-field byte totals) independently of the byte limits.\n\n### Workarounds\n\nNone.","affected":[{"package":{"name":"undici","ecosystem":"npm","purl":"pkg:npm/undici"},"ranges":[{"type":"SEMVER","events":[{"introduced":"6.5.0"},{"fixed":"6.29.1"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-4qv8-2p9j-2685/GHSA-4qv8-2p9j-2685.json"}},{"package":{"name":"undici","ecosystem":"npm","purl":"pkg:npm/undici"},"ranges":[{"type":"SEMVER","events":[{"introduced":"7.0.0"},{"fixed":"7.30.1"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-4qv8-2p9j-2685/GHSA-4qv8-2p9j-2685.json"}},{"package":{"name":"undici","ecosystem":"npm","purl":"pkg:npm/undici"},"ranges":[{"type":"SEMVER","events":[{"introduced":"8.0.0"},{"fixed":"8.12.2"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-4qv8-2p9j-2685/GHSA-4qv8-2p9j-2685.json"}}],"references":[{"type":"WEB","url":"https://github.com/nodejs/undici/security/advisories/GHSA-4qv8-2p9j-2685"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-109924"},{"type":"WEB","url":"https://github.com/nodejs/undici/commit/299162740d5f39120092277e70efacb4d151c1c6"},{"type":"WEB","url":"https://github.com/nodejs/undici/commit/789ef26461c648480433846607154f52d74ec9ab"},{"type":"WEB","url":"https://github.com/nodejs/undici/commit/c43b23fdc6b37e1283d4347408bb16800f867d9e"},{"type":"WEB","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"PACKAGE","url":"https://github.com/nodejs/undici"},{"type":"WEB","url":"https://github.com/nodejs/undici/releases/tag/v6.29.1"},{"type":"WEB","url":"https://github.com/nodejs/undici/releases/tag/v7.30.1"},{"type":"WEB","url":"https://github.com/nodejs/undici/releases/tag/v8.12.2"}],"database_specific":{"cwe_ids":["CWE-770"],"github_reviewed":true,"github_reviewed_at":"2026-10-23T22:13:29Z","nvd_published_at":"2026-10-15T19:17:22Z","severity":"MODERATE"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}