{"api_version":"1","generated_at":"2026-08-18T11:35:15+00:00","cve":"CVE-2026-68155","urls":{"html":"https://cve.report/CVE-2026-68155","api":"https://cve.report/api/cve/CVE-2026-68155.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-68155","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-68155"},"summary":{"title":"libceph: Reject monmaps advertising zero monitors","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nlibceph: Reject monmaps advertising zero monitors\n\nA message of type CEPH_MSG_MON_MAP contains a monmap that is sent from a\nmonitor to the client. This monmap contains information about the\nexisting monitors in the cluster. Currently, a monmap indicating that\nthere are zero monitors in the cluster is treated as valid. However, it\nis impossible to have zero monitors in the cluster and still receive a\nvalid monmap from a monitor. Therefore, such a monmap must be corrupted\nand should be treated as invalid. Furthermore, a monmap with a monitor\ncount of zero can subsequently crash the client when attempting to open\na session with a monitor in __open_session(). This happens because the\n\"BUG_ON(monc->monmap->num_mon < 1)\" assertion in pick_new_mon() is\ntriggered.\n\nThis patch extends a check in ceph_monmap_decode() to also reject\narriving mon_maps with num_mon == 0 rather than only with\nnum_mon > CEPH_MAX_MON.\n\n[ idryomov: drop \"log output for unusual values of num_mon\" part ]","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-10 13:20:01","updated_at":"2026-08-18 07:16:50"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.5","severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.5","severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","data":{"baseScore":7.5,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/40480eee361ed9676b3f844d532ac28b47251634","name":"https://git.kernel.org/stable/c/40480eee361ed9676b3f844d532ac28b47251634","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/cd0d41bc569632eaaeccde9d2a6bc919ec00c407","name":"https://git.kernel.org/stable/c/cd0d41bc569632eaaeccde9d2a6bc919ec00c407","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/0591a15815b498be628a937146e44487d599ba33","name":"https://git.kernel.org/stable/c/0591a15815b498be628a937146e44487d599ba33","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e67e8b694872c9bc66996040f9de9242f6236ed9","name":"https://git.kernel.org/stable/c/e67e8b694872c9bc66996040f9de9242f6236ed9","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/3b249546f59c3d6d3592c10657f82bc3f1faa07c","name":"https://git.kernel.org/stable/c/3b249546f59c3d6d3592c10657f82bc3f1faa07c","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-68155","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-68155","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected ba75bb98cfb93b62c54af25bf67ff90857264bbe 0591a15815b498be628a937146e44487d599ba33 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected ba75bb98cfb93b62c54af25bf67ff90857264bbe cd0d41bc569632eaaeccde9d2a6bc919ec00c407 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected ba75bb98cfb93b62c54af25bf67ff90857264bbe e67e8b694872c9bc66996040f9de9242f6236ed9 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected ba75bb98cfb93b62c54af25bf67ff90857264bbe 3b249546f59c3d6d3592c10657f82bc3f1faa07c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected ba75bb98cfb93b62c54af25bf67ff90857264bbe 40480eee361ed9676b3f844d532ac28b47251634 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2.6.34","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 2.6.34 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.148 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.101 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.42 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.6 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"68155","cve":"CVE-2026-68155","epss":"0.006030000","percentile":"0.459950000","score_date":"2026-08-17","updated_at":"2026-08-18 00:11:47"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/ceph/mon_client.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"0591a15815b498be628a937146e44487d599ba33","status":"affected","version":"ba75bb98cfb93b62c54af25bf67ff90857264bbe","versionType":"git"},{"lessThan":"cd0d41bc569632eaaeccde9d2a6bc919ec00c407","status":"affected","version":"ba75bb98cfb93b62c54af25bf67ff90857264bbe","versionType":"git"},{"lessThan":"e67e8b694872c9bc66996040f9de9242f6236ed9","status":"affected","version":"ba75bb98cfb93b62c54af25bf67ff90857264bbe","versionType":"git"},{"lessThan":"3b249546f59c3d6d3592c10657f82bc3f1faa07c","status":"affected","version":"ba75bb98cfb93b62c54af25bf67ff90857264bbe","versionType":"git"},{"lessThan":"40480eee361ed9676b3f844d532ac28b47251634","status":"affected","version":"ba75bb98cfb93b62c54af25bf67ff90857264bbe","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/ceph/mon_client.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"2.6.34"},{"lessThan":"2.6.34","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.148","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.101","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.42","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.6","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.148","versionStartIncluding":"2.6.34","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.101","versionStartIncluding":"2.6.34","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.42","versionStartIncluding":"2.6.34","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.6","versionStartIncluding":"2.6.34","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2","versionStartIncluding":"2.6.34","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nlibceph: Reject monmaps advertising zero monitors\n\nA message of type CEPH_MSG_MON_MAP contains a monmap that is sent from a\nmonitor to the client. This monmap contains information about the\nexisting monitors in the cluster. Currently, a monmap indicating that\nthere are zero monitors in the cluster is treated as valid. However, it\nis impossible to have zero monitors in the cluster and still receive a\nvalid monmap from a monitor. Therefore, such a monmap must be corrupted\nand should be treated as invalid. Furthermore, a monmap with a monitor\ncount of zero can subsequently crash the client when attempting to open\na session with a monitor in __open_session(). This happens because the\n\"BUG_ON(monc->monmap->num_mon < 1)\" assertion in pick_new_mon() is\ntriggered.\n\nThis patch extends a check in ceph_monmap_decode() to also reject\narriving mon_maps with num_mon == 0 rather than only with\nnum_mon > CEPH_MAX_MON.\n\n[ idryomov: drop \"log output for unusual values of num_mon\" part ]"}],"metrics":[{"cvssV3_1":{"baseScore":7.5,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:N - The bug is reached when libceph decodes CEPH_MSG_MON_MAP from a remote Ceph monitor over the kernel client's established TCP/msgr2 session (mon_dispatch -> ceph_monc_handle_map -> ceph_monmap_decode), which is a network protocol attack surface on CephFS/RBD/cloud nodes.\nAC:L - An attacker who can send monitor protocol messages only needs to set num_mon=0 in the monmap; once accepted, any later session reopen (keepalive timeout, hunt, or connection fault) deterministically hits BUG_ON in pick_new_mon without races or special memory layout.\nPR:N - In the highest-impact scenario a malicious or compromised Ceph monitor (or equivalent authenticated cluster peer) sends the malformed monmap to already-connected kernel clients; the attacker needs no local privileges on the victim host.\nUI:N - After a Ceph client session exists, monmap updates are delivered and processed automatically by the kernel monitor client; no further mount, open, or other victim interaction is required to accept the bad map and later crash on reconnect.\nS:U - Exploitation causes a kernel BUG/panic within the same kernel security domain and does not cross VM, container, IOMMU, or other security boundaries.\nC:N - The failure mode is a BUG_ON assertion in pick_new_mon when num_mon is zero; there is no memory corruption, out-of-bounds access, or other information disclosure primitive on the vulnerable path.\nI:N - Accepting num_mon==0 only stores an empty monmap and later triggers a deliberate kernel BUG; attacker input does not corrupt or modify arbitrary kernel memory or enable code execution.\nA:H - BUG_ON(monc->monmap->num_mon < 1) in pick_new_mon during __open_session causes a kernel oops/panic, fully denying availability of the affected host until reboot."}]}],"providerMetadata":{"dateUpdated":"2026-08-18T06:55:41.963Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/0591a15815b498be628a937146e44487d599ba33"},{"url":"https://git.kernel.org/stable/c/cd0d41bc569632eaaeccde9d2a6bc919ec00c407"},{"url":"https://git.kernel.org/stable/c/e67e8b694872c9bc66996040f9de9242f6236ed9"},{"url":"https://git.kernel.org/stable/c/3b249546f59c3d6d3592c10657f82bc3f1faa07c"},{"url":"https://git.kernel.org/stable/c/40480eee361ed9676b3f844d532ac28b47251634"}],"title":"libceph: Reject monmaps advertising zero monitors","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-68155","datePublished":"2026-08-10T11:59:21.200Z","dateReserved":"2026-07-30T09:28:09.371Z","dateUpdated":"2026-08-18T06:55:41.963Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-10 13:20:01","lastModifiedDate":"2026-08-18 07:16:50","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":3.6}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"68155","Ordinal":"1","Title":"libceph: Reject monmaps advertising zero monitors","CVE":"CVE-2026-68155","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"68155","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nlibceph: Reject monmaps advertising zero monitors\n\nA message of type CEPH_MSG_MON_MAP contains a monmap that is sent from a\nmonitor to the client. This monmap contains information about the\nexisting monitors in the cluster. Currently, a monmap indicating that\nthere are zero monitors in the cluster is treated as valid. However, it\nis impossible to have zero monitors in the cluster and still receive a\nvalid monmap from a monitor. Therefore, such a monmap must be corrupted\nand should be treated as invalid. Furthermore, a monmap with a monitor\ncount of zero can subsequently crash the client when attempting to open\na session with a monitor in __open_session(). This happens because the\n\"BUG_ON(monc->monmap->num_mon < 1)\" assertion in pick_new_mon() is\ntriggered.\n\nThis patch extends a check in ceph_monmap_decode() to also reject\narriving mon_maps with num_mon == 0 rather than only with\nnum_mon > CEPH_MAX_MON.\n\n[ idryomov: drop \"log output for unusual values of num_mon\" part ]","Type":"Description","Title":"libceph: Reject monmaps advertising zero monitors"}]}}}