CVE-2026-5773

#include <stdio.h> #include <curl/curl.h> int main(void) { CURL *curl; CURLcode res; curl_global_init(CURL_GLOBAL_DEFAULT); curl = curl_easy_init(); if(curl) { // Step 1: Initiate a transfer to Share A curl_easy_setopt(curl, CURLOPT_URL, "smb://server/share1/secret.txt"); curl_easy_setopt(curl, CURLOPT_USERNAME, "user"); curl_easy_setopt(curl, CURLOPT_PASSWORD, "pass"); res = curl_easy_perform(curl); // The connection is returned to the pool, associated with share1 context // Step 2: Initiate a transfer to Share B // Vulnerability: libcurl may reuse the connection from Share A for Share B curl_easy_setopt(curl, CURLOPT_URL, "smb://server/share2/public.txt"); res = curl_easy_perform(curl); if(res != CURLE_OK) fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res)); curl_easy_cleanup(curl); } curl_global_cleanup(); return 0; }

{"cve": {"id": "CVE-2026-5773", "sourceIdentifier": "2499f714-1537-4658-8207-48ae4bb9eae9", "published": "2026-05-13T13:01:56.307", "lastModified": "2026-05-13T19:13:14.097", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "libcurl might in some circumstances reuse the wrong connection for SMB(S)\ntransfers.\n\nlibcurl features a pool of recent connections so that subsequent requests can\nreuse an existing connection to avoid overhead.\n\nWhen reusing a connection a range of criteria must be met. Due to a logical\nerror in the code, a network transfer operation that was requested by an\napplication could wrongfully reuse an existing SMB connection to the same\nserver that was using a different 'share' than the new subsequent transfer\nshould.\n\nThis could in unlucky situations lead to the download of the wrong file or the\nupload of a file to the wrong place. When this happens, the same credentials\nare used and the server name is the same."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 3.6}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-918"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.40.0", "versionEndExcluding": "8.20.0", "matchCriteriaId": "ACA618E8-E657-401D-8884-FE82245671E2"}]}]}], "references": [{"url": "https://curl.se/docs/CVE-2026-5773.html", "source": "2499f714-1537-4658-8207-48ae4bb9eae9", "tags": ["Patch", "Vendor Advisory"]}, {"url": "https://curl.se/docs/CVE-2026-5773.json", "source": "2499f714-1537-4658-8207-48ae4bb9eae9", "tags": ["Vendor Advisory"]}, {"url": "https://hackerone.com/reports/3650689", "source": "2499f714-1537-4658-8207-48ae4bb9eae9", "tags": ["Exploit", "Issue Tracking", "Third Party Advisory"]}, {"url": "http://www.openwall.com/lists/oss-security/2026/04/29/9", "source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Mailing List", "Patch", "Third Party Advisory"]}, {"url": "https://hackerone.com/reports/3650689", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Issue Tracking", "Third Party Advisory"]}]}}