CVE-2026-39396

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{"affected": [{"affectedData": [{"product": "openbao", "vendor": "openbao", "versions": [{"status": "affected", "version": "< 2.5.3"}]}], "source": "security-advisories@github.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:openbao:openbao:*:*:*:*:*:*:*:*", "matchCriteriaId": "FB9CD431-A4A7-47AC-8111-76D4F60A9D07", "versionEndExcluding": "2.5.3", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "OpenBao is an open source identity-based secrets management system. Prior to version 2.5.3, `ExtractPluginFromImage()` in OpenBao's OCI plugin downloader extracts a plugin binary from a container image by streaming decompressed tar data via `io.Copy` with no upper bound on the number of bytes written. An attacker who controls or compromises the OCI registry referenced in the victim's configuration can serve a crafted image containing a decompression bomb that decompresses to an arbitrarily large file. The SHA256 integrity check occurs after the full file is written to disk, meaning the hash mismatch is detected only after the damage (disk exhaustion) has already occurred. This allow the attacker to replace **legit plugin image** with no need to change its signature. Version 2.5.3 contains a patch."}, {"lang": "es", "value": "OpenBao es un sistema de gesti\u00f3n de secretos basado en identidad de c\u00f3digo abierto. Antes de la versi\u00f3n 2.5.3, \u2019ExtractPluginFromImage()\u2019 en el descargador de plugins OCI de OpenBao extrae un binario de plugin de una imagen de contenedor mediante la transmisi\u00f3n de datos tar descomprimidos a trav\u00e9s de \u2019io.Copy\u2019 sin un l\u00edmite superior en el n\u00famero de bytes escritos. Un atacante que controla o compromete el registro OCI referenciado en la configuraci\u00f3n de la v\u00edctima puede servir una imagen manipulada que contiene una bomba de descompresi\u00f3n que se descomprime en un archivo arbitrariamente grande. La verificaci\u00f3n de integridad SHA256 ocurre despu\u00e9s de que el archivo completo se escribe en el disco, lo que significa que la falta de coincidencia del hash se detecta solo despu\u00e9s de que el da\u00f1o (agotamiento del disco) ya ha ocurrido. Esto permite al atacante reemplazar la imagen de plugin leg\u00edtima sin necesidad de cambiar su firma. La versi\u00f3n 2.5.3 contiene un parche."}], "id": "CVE-2026-39396", "lastModified": "2026-11-11T23:10:00.263", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "LOW", "baseScore": 3.1, "baseSeverity": "LOW", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L", "version": "3.1"}, "exploitabilityScore": 1.6, "impactScore": 1.4, "source": "security-advisories@github.com", "type": "Secondary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 6.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-39396", "options": [{"exploitation": "poc"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-04-21T15:57:04.802504Z", "version": "2.0.3"}}]}, "published": "2026-04-21T01:16:06.507", "references": [{"source": "security-advisories@github.com", "tags": ["Exploit", "Vendor Advisory"], "url": "https://github.com/openbao/openbao/security/advisories/GHSA-r65v-xgwc-g56j"}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Vendor Advisory"], "url": "https://github.com/openbao/openbao/security/advisories/GHSA-r65v-xgwc-g56j"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-400"}, {"lang": "en", "value": "CWE-674"}, {"lang": "en", "value": "CWE-770"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,2.5.3)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "openbao", "source": "cna", "vendor": "openbao"}, "product": "openbao", "vendor": "openbao"}], "analysis": {"en": {"generated_at": "2026-04-21T23:10:07.711815+00:00", "value": {"mitigation_remediation": ["Upgrade OpenBao to version 2.5.3 or later, which limits the amount of data written during extraction.", "Restrict access to the OCI registry your OpenBao instance uses by enabling authentication and enabling TLS, so that only trusted registries can supply images.", "Temporarily disable the OCI plugin extraction feature until a patched version is available, or use an alternate trusted source for plugin binaries."], "summary": {"action": "Patch", "impact": "Denial of Service through disk exhaustion (and possible unauthorized plugin replacement)."}, "threat_synthesis": {"affected_systems": "This flaw affects all deployments of the openbao product that use the OCI plugin downloader, specifically any instance running OpenBao before version 2.5.3. The affected vendor and product are OpenBao, an open\u2011source identity\u2011based secrets management system.", "description_and_impact": "OpenBao\u2019s OCI plugin downloader performs an unbounded io.Copy when extracting a plugin binary from a container image. An attacker who can supply a malicious image to the OCI registry can embed a decompression bomb that expands into an arbitrarily large file. Because the SHA256 integrity check is only performed after the file has been fully written, the hash mismatch is detected only after disk space has been exhausted. The result is a denial\u2011of\u2011service condition and the attacker can replace a legitimate plugin image without altering its signature.", "risk_and_exploitability": "The CVSS score is 3.1, indicating a low severity. The EPSS score is <1%, and the vulnerability is not listed in the CISA KEV catalog. The attack requires the ability to control or compromise the OCI registry referenced by the victim; once a crafted image is served, the unbounded copy will drain disk space. The impact is limited to the service process that performs the extraction, but repeated or automated attacks could cripple the host and allow the attacker to replace the plugin binary after the integrity check fails."}}}}, "created": "2026-04-21T02:30:25.669241+00:00", "updated": "2026-04-21T23:15:03.122392+00:00", "vendors": ["openbao", "openbao$PRODUCT$openbao"]}