{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-112021", "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "state": "PUBLISHED", "assignerShortName": "VulnCheck", "dateReserved": "2026-10-18T01:24:56.329Z", "datePublished": "2026-10-18T11:38:40.652Z", "dateUpdated": "2026-10-18T11:38:40.652Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "shortName": "VulnCheck", "dateUpdated": "2026-10-18T11:38:40.652Z"}, "datePublic": "2026-07-08T00:00:00.000Z", "title": "snac2 before 2.93 Heap-Based Buffer Overflow via JSON Parser _xs_json_load_lexer()", "descriptions": [{"lang": "en", "value": "snac2 before 2.93 contains a heap-based buffer overflow vulnerability in _xs_json_load_lexer() that allows unauthenticated remote attackers to corrupt heap memory by sending JSON strings containing a \\u0000 escape. Attackers can send a single crafted application/activity+json POST to activitypub_post_handler(), which parses it before signature checks, overflowing heap allocations and crashing the server."}], "problemTypes": [{"descriptions": [{"lang": "en", "description": "Heap-based Buffer Overflow", "cweId": "CWE-122", "type": "CWE"}]}], "affected": [{"vendor": "grunfink", "product": "snac2", "defaultStatus": "unaffected", "versions": [{"version": "0", "lessThan": "2.93", "status": "affected", "versionType": "custom"}], "repo": "https://codeberg.org/grunfink/snac2"}], "metrics": [{"format": "CVSS", "cvssV4_0": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "baseScore": 8.7, "baseSeverity": "HIGH"}}, {"format": "CVSS", "cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH"}}], "references": [{"url": "https://nullenvk.pl/posts/02-snac2-json", "tags": ["technical-description"]}, {"url": "https://gist.github.com/nullenvk/2bf288e2d34cb3d4b7143e61dbf7d90b", "tags": ["exploit"]}, {"url": "https://codeberg.org/grunfink/snac2/src/tag/2.92/xs_json.h#L283-L285", "tags": ["technical-description"]}, {"url": "https://codeberg.org/grunfink/snac2/commit/ec2c5c2046e0381bc942ec5d0d05ec861fe377e7", "tags": ["patch"]}, {"url": "https://codeberg.org/grunfink/snac2/releases/tag/2.93", "tags": ["release-notes"]}, {"url": "https://codeberg.org/grunfink/snac2", "tags": ["product"]}, {"name": "VulnCheck Advisory: snac2 before 2.93 Heap-Based Buffer Overflow via JSON Parser _xs_json_load_lexer()", "tags": ["third-party-advisory"], "url": "https://www.vulncheck.com/advisories/snac2-before-2.93-heap-based-buffer-overflow-via-json-parser-xs-json-load-lexer"}], "credits": [{"lang": "en", "value": "nullenvk", "type": "finder"}], "x_generator": {"engine": "vulncheck-endgame"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "snac2", "repo": "https://codeberg.org/grunfink/snac2", "vendor": "grunfink", "versions": [{"lessThan": "2.93", "status": "affected", "version": "0", "versionType": "custom"}]}], "source": "disclosure@vulncheck.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "snac2 before 2.93 contains a heap-based buffer overflow vulnerability in _xs_json_load_lexer() that allows unauthenticated remote attackers to corrupt heap memory by sending JSON strings containing a \\u0000 escape. Attackers can send a single crafted application/activity+json POST to activitypub_post_handler(), which parses it before signature checks, overflowing heap allocations and crashing the server."}], "id": "CVE-2026-112021", "lastModified": "2026-10-18T12:17:15.200", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 3.6, "source": "disclosure@vulncheck.com", "type": "Primary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 8.7, "baseSeverity": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "disclosure@vulncheck.com", "type": "Secondary"}]}, "published": "2026-10-18T12:17:15.200", "references": [{"source": "disclosure@vulncheck.com", "url": "https://codeberg.org/grunfink/snac2"}, {"source": "disclosure@vulncheck.com", "url": "https://codeberg.org/grunfink/snac2/commit/ec2c5c2046e0381bc942ec5d0d05ec861fe377e7"}, {"source": "disclosure@vulncheck.com", "url": "https://codeberg.org/grunfink/snac2/releases/tag/2.93"}, {"source": "disclosure@vulncheck.com", "url": "https://codeberg.org/grunfink/snac2/src/tag/2.92/xs_json.h#L283-L285"}, {"source": "disclosure@vulncheck.com", "url": "https://gist.github.com/nullenvk/2bf288e2d34cb3d4b7143e61dbf7d90b"}, {"source": "disclosure@vulncheck.com", "url": "https://nullenvk.pl/posts/02-snac2-json"}, {"source": "disclosure@vulncheck.com", "url": "https://www.vulncheck.com/advisories/snac2-before-2.93-heap-based-buffer-overflow-via-json-parser-xs-json-load-lexer"}], "sourceIdentifier": "disclosure@vulncheck.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-122"}], "source": "disclosure@vulncheck.com", "type": "Primary"}]}

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