{"api_version":"1","generated_at":"2026-08-21T06:13:49+00:00","cve":"CVE-2026-77640","urls":{"html":"https://cve.report/CVE-2026-77640","api":"https://cve.report/api/cve/CVE-2026-77640.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-77640","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-77640"},"summary":{"title":"CVE-2026-77640","description":"tor before 0.4.9.9 was prone to an infinite loop when decompressing a truncated zlib/gzip  stream with done=1. A truncated stream never reaches Z_STREAM_END,  causing zlib to return Z_BUF_ERROR with no input remaining, which  buf_add_compress() mistook for a full output buffer and retried forever. Fixed by returning TOR_COMPRESS_ERROR in that case so the caller can abort cleanly. This is TROVE-2026-021.","state":"PUBLISHED","assigner":"mitre","published_at":"2026-08-20 21:17:11","updated_at":"2026-08-20 21:17:11"},"problem_types":["CWE-1284","CWE-1284 CWE-1284 Improper Validation of Specified Quantity in Input"],"metrics":[{"version":"3.1","source":"cve@mitre.org","type":"Secondary","score":"3.7","severity":"LOW","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","baseScore":3.7,"baseSeverity":"LOW","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"LOW"}},{"version":"3.1","source":"CNA","type":"CVSS","score":"3.7","severity":"LOW","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","data":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":3.7,"baseSeverity":"LOW","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","version":"3.1"}}],"references":[{"url":"https://gitlab.torproject.org/tpo/core/tor/-/raw/tor-0.4.9.9/ChangeLog","name":"https://gitlab.torproject.org/tpo/core/tor/-/raw/tor-0.4.9.9/ChangeLog","refsource":"cve@mitre.org","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-77640","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-77640","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"torproject","product":"Tor","version":"affected 0.2.6.1-alpha 0.4.9.9 custom","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Tor","vendor":"torproject","versions":[{"lessThan":"0.4.9.9","status":"affected","version":"0.2.6.1-alpha","versionType":"custom"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:torproject:tor:*:*:*:*:*:*:*:*","versionEndExcluding":"0.4.9.9","versionStartIncluding":"0.2.6.1-alpha","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"tor before 0.4.9.9 was prone to an infinite loop when decompressing a truncated zlib/gzip  stream with done=1. A truncated stream never reaches Z_STREAM_END,  causing zlib to return Z_BUF_ERROR with no input remaining, which  buf_add_compress() mistook for a full output buffer and retried forever. Fixed by returning TOR_COMPRESS_ERROR in that case so the caller can abort cleanly. This is TROVE-2026-021."}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":3.7,"baseSeverity":"LOW","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","version":"3.1"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-1284","description":"CWE-1284 Improper Validation of Specified Quantity in Input","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-08-20T21:02:36.470Z","orgId":"8254265b-2729-46b6-b9e3-3dfca2d5bfca","shortName":"mitre"},"references":[{"url":"https://gitlab.torproject.org/tpo/core/tor/-/raw/tor-0.4.9.9/ChangeLog"}],"x_generator":{"engine":"CVE-Request-form 0.0.1"}}},"cveMetadata":{"assignerOrgId":"8254265b-2729-46b6-b9e3-3dfca2d5bfca","assignerShortName":"mitre","cveId":"CVE-2026-77640","datePublished":"2026-08-20T21:02:36.470Z","dateReserved":"2026-08-20T21:02:36.115Z","dateUpdated":"2026-08-20T21:02:36.470Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-20 21:17:11","lastModifiedDate":"2026-08-20 21:17:11","problem_types":["CWE-1284","CWE-1284 CWE-1284 Improper Validation of Specified Quantity in Input"],"metrics":{"cvssMetricV31":[{"source":"cve@mitre.org","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","baseScore":3.7,"baseSeverity":"LOW","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"LOW"},"exploitabilityScore":2.2,"impactScore":1.4}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"77640","Ordinal":"1","Title":"CVE-2026-77640","CVE":"CVE-2026-77640","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"77640","Ordinal":"1","NoteData":"tor before 0.4.9.9 was prone to an infinite loop when decompressing a truncated zlib/gzip  stream with done=1. A truncated stream never reaches Z_STREAM_END,  causing zlib to return Z_BUF_ERROR with no input remaining, which  buf_add_compress() mistook for a full output buffer and retried forever. Fixed by returning TOR_COMPRESS_ERROR in that case so the caller can abort cleanly. This is TROVE-2026-021.","Type":"Description","Title":"CVE-2026-77640"}]}}}