{"id":"CVE-2026-58270","revision":null,"records":[{"revision":"3c30b3e3a012443684e0a8690beab297","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-58270","aliases":[],"title":"Sync-in Server has a ReDoS via Unsanitized Regex in Sync Diff `pathFilters`","description":"Sync-in Server is an open-source platform for file storage, sharing, collaboration, and syncing. Prior to version 2.4.0, the sync diff endpoint compiles a user-supplied string into a `RegExp` with no complexity validation. A catastrophic-backtracking pattern (e.g. `^(a+)+b`) blocks the Node.js event loop, making the entire server unresponsive to all users until the container is restarted. Version 2.4.0 patches the issue.","state":0,"publishedAt":"2026-09-21T20:28:53.535+00:00","modifiedAt":"2026-09-22T14:06:46.587+00:00","affected":[{"ecosystem":"Vendor product","name":"server","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"Sync-in\",\n                    \"product\": \"server\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 2.4.0\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":6.5,"severity":"MEDIUM"}],"references":["https://github.com/Sync-in/server/security/advisories/GHSA-jx63-h26r-8cph"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-58270","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-58270","identifiers":["CVE-2026-58270"]},"retained":false,"historicalAffected":[]},{"revision":"10112eaf06df408586dbf62ee36289c0","observedAt":"2026-11-11T14:59:45.626+00:00","statement":{"source":"euvd","id":"EUVD-2026-84198","aliases":["CVE-2026-58270","GHSA-jx63-h26r-8cph"],"title":"Sync-in Server is an open-source platform for file storage, sharing, collaboration, and syncing. Prior to version 2.4.0, the sync diff endpoint compiles a user-supplied string into a `RegExp` with no complexity validation. A catastrophic-ba…","description":"Sync-in Server is an open-source platform for file storage, sharing, collaboration, and syncing. Prior to version 2.4.0, the sync diff endpoint compiles a user-supplied string into a `RegExp` with no complexity validation. A catastrophic-backtracking pattern (e.g. `^(a+)+b`) blocks the Node.js event loop, making the entire server unresponsive to all users until the container is restarted. Version 2.4.0 patches the issue.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":6.5,"severity":null}],"references":["https://github.com/Sync-in/server/security/advisories/GHSA-jx63-h26r-8cph"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-84198","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Sep 21, 2026, 8:28:53 PM","dateUpdated":"Sep 22, 2026, 2:06:46 PM"},"relatedAdvisories":[],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2026-84198","identifiers":["EUVD-2026-84198","CVE-2026-58270","GHSA-jx63-h26r-8cph"]},"retained":false,"historicalAffected":[]},{"revision":"12345ec5826548739fd1bcef9ce674bc","observedAt":"2026-10-25T14:19:16.843+00:00","statement":{"source":"nvd","id":"CVE-2026-58270","aliases":[],"title":"Sync-in Server is an open-source platform for file storage, sharing, collaboration, and syncing. Prior to version 2.4.0, the sync diff endpoint compiles a user-supplied string into a `RegExp` with no complexity validation. A catastrophic-ba…","description":"Sync-in Server is an open-source platform for file storage, sharing, collaboration, and syncing. Prior to version 2.4.0, the sync diff endpoint compiles a user-supplied string into a `RegExp` with no complexity validation. 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Version 2.4.0 patches the issue.","state":0,"publishedAt":"2026-09-21T21:17:06.06+00:00","modifiedAt":"2026-09-24T21:25:27.05+00:00","affected":[],"metrics":[{"system":"CVSS 3.1 · security-advisories@github.com · Secondary","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":6.5,"severity":"MEDIUM"}],"references":["https://github.com/Sync-in/server/security/advisories/GHSA-jx63-h26r-8cph"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-58270","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Deferred","weaknesses":["CWE-1333"],"productCriteria":[],"sourceDates":{"published":"2026-09-21T21:17:06.060","lastModified":"2026-09-24T21:25:27.050"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-58270","identifiers":["CVE-2026-58270"]},"retained":false,"historicalAffected":[]},{"revision":"9538a76bc42c4cc48e811de8c6845cb7","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-jx63-h26r-8cph","aliases":["CVE-2026-58270"],"title":"Sync-in Server has a ReDoS via Unsanitized Regex in Sync Diff `pathFilters`","description":"**Affected component:** Sync-in Server v2.3.0, `POST /api/app/sync/operation/diff/:id`, vulnerable implementation of `pathFilters` in `backend/src/applications/sync/dtos/sync-operations.dto.ts`.\n\n## Summary\n\nIn the vulnerable version, the sync diff endpoint accepted a user-controlled regex pattern through `pathFilters` and compiled it into a `RegExp` without complexity validation. The resulting regex was then executed synchronously against relative file paths during diff generation.\n\nA catastrophic-backtracking pattern, such as `^(a+)+b`, can block the affected Node.js event loop when evaluated against a worst-case path shape. In a single-process deployment, this can make the server unavailable to other users while the regex evaluation is running. Repeated malicious requests can sustain the denial of service.\n\n## Details\n\n`SyncDiffDto` transformed user input directly into a `RegExp` without validating regex complexity:\n```typescript\n// backend/src/applications/sync/dtos/sync-operations.dto.ts\n@IsOptional()\n@Transform(({ value }) => (typeof value === 'string' && value.length > 0 ? new RegExp(value, 'i') : null))\npathFilters?: RegExp = null\n```\nThe compiled regex was then executed synchronously during sync diff traversal:\n```typescript\n// backend/src/applications/sync/services/sync-manager.service.ts\nif (ctx.syncDiff.pathFilters && ctx.syncDiff.pathFilters.test(filePath)) {\n```\nBecause `.test()` is synchronous, a catastrophic-backtracking pattern can block the Node.js event loop for the duration of the regex evaluation.\n\nThe impact depends on the file paths being tested. For example, the pattern `^(a+)+b` is most effective when the sync tree contains a relative path beginning with a long sequence of `a` characters and not followed by `b`.\n\n## PoC\n\n**Prerequisites:** Valid non-guest account, a registered sync client, and a sync path containing at least one file or directory whose relative path triggers catastrophic backtracking for the supplied pattern.\n\nFor the payload `^(a+)+b`, an effective test case is a path containing a long name made of repeated `a` characters.\n\n**Steps:**\n\n1. Register a sync client: `POST /api/app/sync/register` with credentials and `clientId`.\n2. Authenticate: `POST /api/app/sync/auth/cookie` to get a JWT with `clientId` embedded.\n3. Create or use a sync path targeting an application-managed directory containing files.\n4. Ensure the sync path contains a worst-case filename or directory name for the regex, for example a long sequence of `a` characters.\n5. Send a diff request with the ReDoS pattern:\n```http\nPOST /api/app/sync/operation/diff/1\nContent-Type: application/json\nsync-in-csrf: <csrf-token>\nCookie: sync-in-access=<jwt>\n\n{\"secureDiff\":false,\"firstSync\":true,\"defaultFilters\":[],\"pathFilters\":\"^(a+)+b\",\"snapshot\":{}}\n```\n**Evidence from live test on Sync-in Server v2.3.0, Node.js v24.16.0:**\n```text\n[+] Baseline (no pathFilters): 0.019s, 15 files\n[*] Sending ReDoS pattern: ^(a+)+b\n[!] TIMEOUT after 20.022s - ReDoS CONFIRMED\n\n# Server state during ReDoS:\n$ docker stats sync-in --no-stream\nCONTAINER   CPU %     MEM USAGE\nsync-in     398.82%   745.2MiB / 7.709GiB\n\n# Other endpoints did not respond during the timeout window:\n$ curl -m 5 http://target:8080/\n(exit code 28 - connection timeout)\n```\nThe container-level CPU spike indicates severe resource saturation while the endpoint was unresponsive. The request timeout demonstrates event-loop blocking during the observed window, but does not by itself prove permanent failure after the malicious request stops.\n\n## Impact\n\nAn authenticated user with desktop sync access can submit a malicious `pathFilters` regex that blocks the affected Node.js event loop during sync diff generation.\n\nIn a single-process deployment, this can prevent other HTTP requests, including health checks, from receiving responses while the regex evaluation is running. Repeated malicious requests can keep the service unavailable and may require administrative intervention.\n\n## Remediation\n\nValidate `pathFilters` before using the resulting regex during diff traversal.\n\nRecommended controls:\n\n- Reject empty or non-string values.\n- Enforce a maximum regex pattern length.\n- Reject invalid regex syntax.\n- Reject unsafe regex patterns using `safe-regex2` or an equivalent safety checker.\n- Return a `BadRequestException` for invalid or unsafe patterns.\n\nExample remediation:\n```typescript\n@IsOptional()\n@Transform(({ value }) => {\n  if (typeof value !== 'string' || value.length === 0) return null\n\n  if (value.length > MAX_PATH_FILTER_PATTERN_LENGTH) {\n    throw new BadRequestException('Path filter pattern is too long')\n  }\n\n  let pathFilter: RegExp\n  try {\n    pathFilter = new RegExp(value, 'i')\n  } catch {\n    throw new BadRequestException('Invalid path filter pattern')\n  }\n\n  if (!isSafePattern(pathFilter)) {\n    throw new BadRequestException('Unsafe path filter pattern')\n  }\n\n  return pathFilter\n})\npathFilters?: RegExp = null\n```\nWhere `isSafePattern` uses `safe-regex2` or equivalent to reject patterns likely to cause catastrophic backtracking, including nested quantifier patterns such as `^(a+)+b`.\n\nA regression test should assert that `^(a+)+b` is rejected before the regex is used against file paths.","state":0,"publishedAt":"2026-09-22T14:47:56+00:00","modifiedAt":"2026-09-22T15:00:48.9095436+00:00","affected":[{"ecosystem":"npm","name":"@sync-in/server","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"2.4.0"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/Sync-in/server/security/advisories/GHSA-jx63-h26r-8cph","https://nvd.nist.gov/vuln/detail/CVE-2026-58270","https://github.com/Sync-in/server/pull/228","https://github.com/Sync-in/server/commit/b1dcaa1d1c1bb17ab6c31a404cc9cead7efdd979","https://github.com/Sync-in/server","https://github.com/Sync-in/server/releases/tag/v2.4.0"],"sourceUrl":"https://github.com/advisories/GHSA-jx63-h26r-8cph","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-jx63-h26r-8cph","identifiers":["GHSA-jx63-h26r-8cph","CVE-2026-58270"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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