CVE-2026-31968

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CRAM is a compressed format which stores DNA sequence alignment data using a variety of encodings and compression methods. For the `VARINT` and `CONST` encodings, incomplete validation of the context in which the encodings were used could result in up to eight bytes being written beyond the end of a heap allocation, or up to eight bytes being written to the location of a one byte variable on the stack, possibly causing the values to adjacent variables to change unexpectedly. Depending on the data stream this could result either in a heap buffer overflow or a stack overflow. If a user opens a file crafted to exploit this issue it could lead to the program crashing, overwriting of data structures on the heap or stack in ways not expected by the program, or changing the control flow of the program. It may be possible to use this to obtain arbitrary code execution. Versions 1.23.1, 1.22.2 and 1.21.1 include fixes for this issue. There is no workaround for this issue."}, {"lang": "es", "value": "HTSlib es una biblioteca para leer y escribir formatos de archivo de bioinform\u00e1tica. CRAM es un formato comprimido que almacena datos de alineaci\u00f3n de secuencias de ADN utilizando una variedad de codificaciones y m\u00e9todos de compresi\u00f3n. Para las codificaciones 'VARINT' y 'CONST', la validaci\u00f3n incompleta del contexto en el que se utilizaron las codificaciones podr\u00eda resultar en la escritura de hasta ocho bytes m\u00e1s all\u00e1 del final de una asignaci\u00f3n de memoria en el mont\u00f3n, o en la escritura de hasta ocho bytes en la ubicaci\u00f3n de una variable de un byte en la pila, posiblemente causando que los valores de las variables adyacentes cambien inesperadamente. Dependiendo del flujo de datos, esto podr\u00eda resultar en un desbordamiento de b\u00fafer en el mont\u00f3n o un desbordamiento de pila. Si un usuario abre un archivo dise\u00f1ado para explotar este problema, podr\u00eda provocar el bloqueo del programa, la sobrescritura de estructuras de datos en el mont\u00f3n o la pila de formas no esperadas por el programa, o el cambio del flujo de control del programa. Podr\u00eda ser posible usar esto para obtener ejecuci\u00f3n de c\u00f3digo arbitrario. Las versiones 1.23.1, 1.22.2 y 1.21.1 incluyen correcciones para este problema. No existe una soluci\u00f3n alternativa para este problema."}], "id": "CVE-2026-31968", "lastModified": "2026-06-17T10:34:51.650", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.1, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 5.2, "source": "nvd@nist.gov", "type": "Primary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 8.8, "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:H/VA:L/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": "LOW", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-31968", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-03-18T19:57:24.242380Z", "version": "2.0.3"}}]}, "published": "2026-03-18T20:16:21.480", "references": [{"source": "security-advisories@github.com", "tags": ["Patch"], "url": "https://github.com/samtools/htslib/commit/0ec436796eca7b4ce7fcc9b77270c102da29bb2e"}, {"source": "security-advisories@github.com", "tags": ["Patch", "Vendor Advisory"], "url": "https://github.com/samtools/htslib/security/advisories/GHSA-cgcm-c9r2-p57j"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-121"}, {"lang": "en", "value": "CWE-122"}, {"lang": "en", "value": "CWE-787"}, {"lang": "en", "value": "CWE-843"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,1.21.1)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[1.22,1.22.2)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "1.23"}}], "enrichment": {"confidence": 100.0, "confidence_source": "cna", "scores": [{"score": 100.0, "source": "cna"}]}, "product": "htslib", "vendor": "samtools"}], "analysis": {"en": {"generated_at": "2026-03-19T18:25:56.607022+00:00", "value": {"mitigation_remediation": ["Upgrade htslib to v1.23.1 or later (or v1.22.2/v1.21.1 if constrained).", "Validate CRAM files and restrict processing to trusted sources; monitor for abnormal crashes or memory corruption."], "summary": {"action": "Patch Immediately", "impact": "Heap/Stack Buffer Overflow with potential arbitrary code execution"}, "threat_synthesis": {"affected_systems": "The issue affects the htslib library used by samtools. Versions earlier than 1.23.1, 1.22.2 and 1.21.1 are vulnerable. The fix is included in v1.23.1, v1.22.2, and v1.21.1.", "description_and_impact": "The vulnerability occurs in HTSlib's CRAM decoder when processing VARINT and CONST encodings; missing validation can allow up to eight bytes to be written beyond the allocated buffer, causing a heap or stack overflow. Attack via a maliciously crafted CRAM file could crash the application, corrupt internal data structures, or modify control flow, potentially leading to arbitrary code execution.", "risk_and_exploitability": "The CVSS score is 8.8, indicating high severity, while the EPSS score is less than 1%, suggesting a low likelihood of exploitation. The vulnerability is not listed in the CISA KEV catalog. Exploitation requires an attacker to supply a maliciously crafted CRAM file that an application using HTSlib will parse; thus the primary vector is a file-based attack."}}}}, "created": "2026-03-19T08:55:40.220978+00:00", "updated": "2026-03-25T11:52:22.630753+00:00", "vendors": ["samtools", "samtools$PRODUCT$htslib"]}