{"id":"CVE-2023-26103","aliases":["EUVD-2023-1335","GHSA-jc97-h3h9-7xh6","JLSEC-2026-101"],"status":"published","title":"Regular Expression Denial of Service in Deno.upgradeWebSocket API","description":"Versions of the package deno before 1.31.0 are vulnerable to Regular Expression Denial of Service (ReDoS) due to the upgradeWebSocket function, which contains regexes in the form of /s*,s*/, used for splitting the Connection/Upgrade header. A specially crafted Connection/Upgrade header can be used to significantly slow down a web socket server.","severity":{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.01229,"percentile":0.69284,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-1333"],"published":"2023-02-25T05:00:01Z","modified":"2026-10-28T02:31:06Z","fixes":[{"ecosystem":"crates.io","package":"deno","fixed_in":["1.31.0"],"sources":["ghsa","osv"]},{"ecosystem":"Julia","package":"Deno_jll","fixed_in":["1.33.4+0"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"crates.io","package":"deno","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.12.0"},{"fixed":"1.31.0"}]}]},{"source":"osv","ecosystem":"crates.io","package":"deno","ranges":[{"type":"SEMVER","events":[{"introduced":"1.12.0"},{"fixed":"1.31.0"}]}]},{"source":"osv","ecosystem":"Julia","package":"Deno_jll","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.33.4+0"}]}]}],"products":[{"vendor":"deno","product":"deno"},{"vendor":"denoland","product":"deno"}],"references":[{"url":"https://security.snyk.io/vuln/SNYK-RUST-DENO-3315970","tags":["x_transferred","Exploit","Technical Description","Third Party Advisory","web"]},{"url":"https://github.com/denoland/deno/blob/2b247be517d789a37e532849e2e40b724af0918f/ext/http/01_http.js%23L395-L409","tags":["x_transferred","Broken Link","web"]},{"url":"https://github.com/denoland/deno/pull/17722","tags":["x_transferred","Patch","fix","web"]},{"url":"https://github.com/denoland/deno/commit/cf06a7c7e672880e1b38598fe445e2c50b4a9d06","tags":["x_transferred","Patch","fix","web"]},{"url":"https://github.com/denoland/deno/releases/tag/v1.31.0","tags":["x_transferred","Release Notes","web"]},{"url":"https://github.com/denoland/deno/security/advisories/GHSA-jc97-h3h9-7xh6","tags":["web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2023-26103","tags":["advisory"]},{"url":"https://github.com/denoland/deno/blob/2b247be517d789a37e532849e2e40b724af0918f/ext/http/01_http.js#L395-L409","tags":["web"]},{"url":"https://github.com/advisories/GHSA-jc97-h3h9-7xh6"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/26xxx/CVE-2023-26103.json","tags":["advisory"]},{"url":"https://github.com/denoland/deno","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2023-26103","description":"Versions of the package deno before 1.31.0 are vulnerable to Regular Expression Denial of Service (ReDoS) due to the upgradeWebSocket function, which contains regexes in the form of /s*,s*/, used for splitting the Connection/Upgrade header. A specially crafted Connection/Upgrade header can be used to significantly slow down a web socket server.\r\r","status":"published","published":"2023-02-25T05:00:01.387Z","modified":"2025-03-11T15:31:01.247Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium","assessor":"cna"}],"cwes":["CWE-1333","CWE-1333"],"updated_at":"2026-11-02T14:35:15.434947Z"}],"euvd":[{"id":"EUVD-2023-1335","description":"Versions of the package deno before 1.31.0 are vulnerable to Regular Expression Denial of Service (ReDoS) due to the upgradeWebSocket function, which contains regexes in the form of /s*,s*/, used for splitting the Connection/Upgrade header. A specially crafted Connection/Upgrade header can be used to significantly slow down a web socket server.\r\r","status":"published","published":"2023-02-25T05:00:01Z","modified":"2025-03-11T15:31:01Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium"}],"updated_at":"2026-11-02T20:53:07.779422Z"}],"ghsa":[{"id":"GHSA-jc97-h3h9-7xh6","title":"Regular Expression Denial of Service in Deno.upgradeWebSocket API","description":"### Impact\nVersions of the package deno before 1.31.0 are vulnerable to Regular Expression Denial of Service (ReDoS) due to the upgradeWebSocket function, which contains regexes in the form of /s*,s*/, used for splitting the Connection/Upgrade header. A specially crafted Connection/Upgrade header can be used to significantly slow down a web socket server. \n\n### Patches\nIt is recommended that users upgrade to Deno 1.31.0.\n\n","status":"published","published":"2023-04-03T17:18:51Z","modified":"2023-04-03T17:18:52Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium"}],"cwes":["CWE-1333"],"updated_at":"2026-11-02T14:36:49.768564Z"}],"nvd":[{"id":"CVE-2023-26103","description":"Versions of the package deno before 1.31.0 are vulnerable to Regular Expression Denial of Service (ReDoS) due to the upgradeWebSocket function, which contains regexes in the form of /s*,s*/, used for splitting the Connection/Upgrade header. A specially crafted Connection/Upgrade header can be used to significantly slow down a web socket server.\r\r","status":"published","published":"2023-02-25T05:15:12.343Z","modified":"2026-06-17T05:42:41.007Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium","assessor":"secondary"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary"}],"cwes":["CWE-1333"],"updated_at":"2026-11-02T14:07:47.623983Z"}],"osv":[{"id":"CVE-2023-26103","description":"Versions of the package deno before 1.31.0 are vulnerable to Regular Expression Denial of Service (ReDoS) due to the upgradeWebSocket function, which contains regexes in the form of /s*,s*/, used for splitting the Connection/Upgrade header. A specially crafted Connection/Upgrade header can be used to significantly slow down a web socket server.\r\r","status":"published","published":"2023-02-25T05:00:01.387Z","modified":"2026-10-28T02:31:06.73747098Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium"}],"cwes":["CWE-1333"],"updated_at":"2026-11-02T15:44:31.135751Z"},{"id":"GHSA-jc97-h3h9-7xh6","title":"Regular Expression Denial of Service in Deno.upgradeWebSocket API","description":"### Impact\nVersions of the package deno before 1.31.0 are vulnerable to Regular Expression Denial of Service (ReDoS) due to the upgradeWebSocket function, which contains regexes in the form of /s*,s*/, used for splitting the Connection/Upgrade header. A specially crafted Connection/Upgrade header can be used to significantly slow down a web socket server. \n\n### Patches\nIt is recommended that users upgrade to Deno 1.31.0.\n\n","status":"published","published":"2023-04-03T17:18:51Z","modified":"2023-11-08T04:11:57.713363Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium"}],"cwes":["CWE-1333"],"updated_at":"2026-11-02T15:46:50.336262Z"},{"id":"JLSEC-2026-101","description":"Versions of the package deno before 1.31.0 are vulnerable to Regular Expression Denial of Service (ReDoS) due to the upgradeWebSocket function, which contains regexes in the form of `/s*,s*/`, used for splitting the Connection/Upgrade header. A specially crafted Connection/Upgrade header can be used to significantly slow down a web socket server.","status":"published","published":"2026-04-14T13:10:46.494Z","modified":"2026-07-25T18:23:46.593550844Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:47:18.159338Z"}]}}