CVE-2021-29991

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{"affected": [{"affectedData": [{"product": "Firefox", "vendor": "Mozilla", "versions": [{"lessThan": "91.0.1", "status": "affected", "version": "unspecified", "versionType": "custom"}]}, {"product": "Thunderbird", "vendor": "Mozilla", "versions": [{"lessThan": "91.0.1", "status": "affected", "version": "unspecified", "versionType": "custom"}]}], "source": "security@mozilla.org"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*", "matchCriteriaId": "D59F66A7-8533-42F9-996F-97F45E06ACA0", "versionEndExcluding": "91.0.1", "vulnerable": true}, {"criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*", "matchCriteriaId": "B434369F-018C-41C1-AC1D-99AE9618238B", "versionEndExcluding": "91.0.1", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Firefox incorrectly accepted a newline in a HTTP/3 header, interpretting it as two separate headers. This allowed for a header splitting attack against servers using HTTP/3. This vulnerability affects Firefox < 91.0.1 and Thunderbird < 91.0.1."}, {"lang": "es", "value": "Firefox aceptaba incorrectamente una nueva l\u00ednea en un encabezado HTTP/3, interpret\u00e1ndola como dos encabezados separados. Esto permit\u00eda un ataque de divisi\u00f3n de encabezados contra servidores que usaban HTTP/3. Esta vulnerabilidad afecta a Firefox versiones anteriores a 91.0.1 y Thunderbird versiones anteriores a 91.0.1"}], "id": "CVE-2021-29991", "lastModified": "2026-06-17T03:48:34.230", "metrics": {"cvssMetricV2": [{"acInsufInfo": false, "baseSeverity": "MEDIUM", "cvssData": {"accessComplexity": "MEDIUM", "accessVector": "NETWORK", "authentication": "NONE", "availabilityImpact": "NONE", "baseScore": 5.8, "confidentialityImpact": "PARTIAL", "integrityImpact": "PARTIAL", "vectorString": "AV:N/AC:M/Au:N/C:P/I:P/A:N", "version": "2.0"}, "exploitabilityScore": 8.6, "impactScore": 4.9, "obtainAllPrivilege": false, "obtainOtherPrivilege": false, "obtainUserPrivilege": false, "source": "nvd@nist.gov", "type": "Primary", "userInteractionRequired": true}], "cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 8.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 5.2, "source": "nvd@nist.gov", "type": "Primary"}]}, "published": "2021-11-03T01:15:07.060", "references": [{"source": "security@mozilla.org", "tags": ["Permissions Required"], "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1724896"}, {"source": "security@mozilla.org", "tags": ["Vendor Advisory"], "url": "https://www.mozilla.org/security/advisories/mfsa2021-37/"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Permissions Required"], "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1724896"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Vendor Advisory"], "url": "https://www.mozilla.org/security/advisories/mfsa2021-37/"}], "sourceIdentifier": "security@mozilla.org", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-444"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "Mozilla: Header Splitting possible with HTTP/3 Responses", "id": "1995267", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1995267"}, "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:N/I:H/A:N", "status": "draft"}, "cwe": "CWE-79", "details": ["Firefox incorrectly accepted a newline in a HTTP/3 header, interpretting it as two separate headers. This allowed for a header splitting attack against servers using HTTP/3. This vulnerability affects Firefox < 91.0.1 and Thunderbird < 91.0.1.", "The Mozilla Foundation Security Advisory describes this flaw as:\nFirefox incorrectly accepted a newline in a HTTP/3 header, interpretting it as two separate headers. This allowed for a header splitting attack against servers using HTTP/3."], "name": "CVE-2021-29991", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Fix deferred", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Fix deferred", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2021-08-18T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2021-29991\nhttps://nvd.nist.gov/vuln/detail/CVE-2021-29991"], "threat_severity": "Important"}

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