CVE-2026-9545

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Potentially leaking sensitive\ninformation."}], "affected": [{"vendor": "curl", "product": "curl", "versions": [{"version": "8.11.0", "status": "affected", "versionType": "semver", "lessThan": "8.14.2"}, {"version": "8.15.0", "status": "affected", "versionType": "semver", "lessThan": "8.16.1"}, {"version": "8.17.0", "status": "affected", "versionType": "semver", "lessThan": "8.20.1"}], "defaultStatus": "unaffected"}, {"vendor": "curl", "product": "curl", "versions": [{"version": "962097b8dd44ed5b9e7984bc1cdffdbdd566857f", "status": "affected", "versionType": "git", "lessThan": "7b9613fa9b1a5e04301a3920eef58e8138dad05e"}], "defaultStatus": "unaffected", "repo": "https://github.com/curl/curl.git"}, {"vendor": "curl", "product": "curl", "versions": [{"version": "8.20.0", "status": "affected"}, {"version": "8.19.0", "status": "affected"}, {"version": "8.18.0", "status": "affected"}, {"version": "8.17.0", "status": "affected"}, {"version": "8.16.0", "status": "affected"}, {"version": "8.15.0", "status": "affected"}, {"version": "8.14.1", "status": "affected"}, {"version": "8.14.0", "status": "affected"}, {"version": "8.13.0", "status": "affected"}, {"version": "8.12.1", "status": "affected"}, {"version": "8.12.0", "status": "affected"}, {"version": "8.11.1", "status": "affected"}, {"version": "8.11.0", "status": "affected"}], "defaultStatus": "unaffected"}], "references": [{"url": "https://curl.se/docs/CVE-2026-9545.json"}, {"url": "https://curl.se/docs/CVE-2026-9545.html"}, {"url": "https://hackerone.com/reports/3752888"}], "x_osv": {"schema_version": "1.5.0", "id": "CURL-CVE-2026-9545", "aliases": ["CVE-2026-9545"], "summary": "exposing HTTP/3 early data", "modified": "2026-09-07T10:34:51.00Z", "database_specific": {"package": "curl", "affects": "both", "URL": "https://curl.se/docs/CVE-2026-9545.json", "www": "https://curl.se/docs/CVE-2026-9545.html", "issue": "https://hackerone.com/reports/3752888", "CWE": {"id": "CWE-200", "desc": "Exposure of Sensitive Information to an Unauthorized Actor"}, "last_affected": "8.20.0", "severity": "Low"}, "published": "2026-06-24T08:00:00.00Z", "affected": [{"ranges": [{"type": "SEMVER", "events": [{"introduced": "8.11.0"}, {"fixed": "8.14.2"}, {"introduced": "8.15.0"}, {"fixed": "8.16.1"}, {"introduced": "8.17.0"}, {"fixed": "8.20.1"}]}, {"type": "GIT", "repo": "https://github.com/curl/curl.git", "events": [{"introduced": "962097b8dd44ed5b9e7984bc1cdffdbdd566857f"}, {"fixed": "7b9613fa9b1a5e04301a3920eef58e8138dad05e"}]}], "versions": ["8.20.0", "8.19.0", "8.18.0", "8.17.0", "8.16.0", "8.15.0", "8.14.1", "8.14.0", "8.13.0", "8.12.1", "8.12.0", "8.11.1", "8.11.0"]}], "credits": [{"name": "Eunsoo Kim (Autonomous Code Security team at Microsoft)", "type": "finder"}, {"name": "Stefan Eissing", "type": "remediation developer"}], "details": "In this scenario, libcurl first uses a proper HTTP/3 server for the initial\ntransfers, and when it makes a second transfer to the same site it has been\nreplaced by the attacker's impostor machine - without a valid certificate.\n\nWhen libcurl returns to the hostname the second time with a cached SSL session\n(`CURLOPT_SSL_SESSIONID_CACHE` is not disabled) and early data enabled (the\n`CURLSSLOPT_EARLYDATA` bit is set in `CURLOPT_SSL_OPTIONS`), libcurl might\nsend off the second request's bytes on that new connection *before* enforcing\nthe certificate verification failure. Potentially leaking sensitive\ninformation."}, "problemTypes": [{"descriptions": [{"lang": "en", "description": "Exposure of Sensitive Information to an Unauthorized Actor", "cweId": "CWE-200", "type": "CWE"}]}], "credits": [{"lang": "en", "value": "Eunsoo Kim (Autonomous Code Security team at Microsoft)", "type": "finder"}, {"lang": "en", "value": "Stefan Eissing", "type": "remediation developer"}], "x_generator": {"engine": "cvelib 1.8.0"}}, "adp": [{"references": [{"url": "https://hackerone.com/reports/3752888", "tags": ["exploit"]}], "metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}}, {"other": {"type": "ssvc", "content": {"timestamp": "2026-07-06T16:52:42.898546Z", "id": "CVE-2026-9545", "options": [{"Exploitation": "poc"}, {"Automatable": "yes"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-07-06T16:53:23.396Z"}}]}}

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Potentially leaking sensitive\ninformation."}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-200", "description": "Exposure of Sensitive Information to an Unauthorized Actor"}]}], "providerMetadata": {"orgId": "2499f714-1537-4658-8207-48ae4bb9eae9", "shortName": "curl", "dateUpdated": "2026-09-15T06:03:31.804Z"}}}, "cveMetadata": {"cveId": "CVE-2026-9545", "state": "PUBLISHED", "dateUpdated": "2026-09-15T06:03:31.804Z", "dateReserved": "2026-05-26T06:45:08.680Z", "assignerOrgId": "2499f714-1537-4658-8207-48ae4bb9eae9", "datePublished": "2026-07-03T06:17:55.931Z", "assignerShortName": "curl"}, "dataVersion": "5.2"}

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{"bugzilla": {"description": "libcurl: libcurl: Information disclosure via cached SSL session and early data", "id": "2496756", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2496756"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.5", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "status": "draft"}, "cwe": "CWE-295", "details": ["In this scenario, libcurl first uses a proper HTTP/3 server for the initial\ntransfers, and when it makes a second transfer to the same site it has been\nreplaced by the attacker's impostor machine - without a valid certificate.\nWhen libcurl returns to the hostname the second time with a cached SSL session\n(`CURLOPT_SSL_SESSIONID_CACHE` is not disabled) and early data enabled (the\n`CURLSSLOPT_EARLYDATA` bit is set in `CURLOPT_SSL_OPTIONS`), libcurl might\nsend off the second request's bytes on that new connection *before* enforcing\nthe certificate verification failure. Potentially leaking sensitive\ninformation.", "A flaw was found in libcurl. An attacker can exploit this by replacing a legitimate HTTP/3 server with an impostor machine. When libcurl attempts a second transfer to the same site with a cached SSL session and early data enabled, it may send sensitive request data before verifying the server's certificate. This could lead to the disclosure of sensitive information to the attacker."], "mitigation": {"lang": "en:us", "value": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability."}, "name": "CVE-2026-9545", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "dotnet8.0", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/a:redhat:jboss_core_services:1", "fix_state": "Affected", "package_name": "libcurl-1.dll", "product_name": "Red Hat JBoss Core Services"}, {"cpe": "cpe:/a:redhat:jboss_core_services:1", "fix_state": "Affected", "package_name": "libcurl.so", "product_name": "Red Hat JBoss Core Services"}], "public_date": "2026-07-03T06:17:55Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-9545\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-9545\nhttps://curl.se/docs/CVE-2026-9545.html\nhttps://curl.se/docs/CVE-2026-9545.json\nhttps://hackerone.com/reports/3752888"], "statement": "This Moderate impact information disclosure flaw in libcurl arises when an application uses HTTP/3 with both SSL session caching and early data enabled. An attacker could exploit this by impersonating a legitimate server, leading to sensitive data being sent before certificate verification fails. This scenario requires specific libcurl configurations that may not be enabled by default in all Red Hat products.", "threat_severity": "Important"}

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