{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-68155", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-30T09:28:09.371Z", "datePublished": "2026-08-10T11:59:21.200Z", "dateUpdated": "2026-08-19T16:30:22.933Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-19T16:30:22.933Z" }, "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": { "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" }, "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." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ceph/mon_client.c" ], "versions": [ { "version": "ba75bb98cfb93b62c54af25bf67ff90857264bbe", "lessThan": "caf082ef8609a6ac26159ce115f55ab7d00231a3", "status": "affected", "versionType": "git" }, { "version": "ba75bb98cfb93b62c54af25bf67ff90857264bbe", "lessThan": "e3ccd4ecab09b22f507f49cb7ed9990c7158ceab", "status": "affected", "versionType": "git" }, { "version": "ba75bb98cfb93b62c54af25bf67ff90857264bbe", "lessThan": "0591a15815b498be628a937146e44487d599ba33", "status": "affected", "versionType": "git" }, { "version": "ba75bb98cfb93b62c54af25bf67ff90857264bbe", "lessThan": "cd0d41bc569632eaaeccde9d2a6bc919ec00c407", "status": "affected", "versionType": "git" }, { "version": "ba75bb98cfb93b62c54af25bf67ff90857264bbe", "lessThan": "e67e8b694872c9bc66996040f9de9242f6236ed9", "status": "affected", "versionType": "git" }, { "version": "ba75bb98cfb93b62c54af25bf67ff90857264bbe", "lessThan": "3b249546f59c3d6d3592c10657f82bc3f1faa07c", "status": "affected", "versionType": "git" }, { "version": "ba75bb98cfb93b62c54af25bf67ff90857264bbe", "lessThan": "40480eee361ed9676b3f844d532ac28b47251634", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ceph/mon_client.c" ], "versions": [ { "version": "2.6.34", "status": "affected" }, { "version": "0", "lessThan": "2.6.34", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.216", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.183", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.148", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.101", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.42", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.6", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "5.15.216" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "6.1.183" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "6.6.148" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "6.12.101" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "6.18.42" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "7.1.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.34", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/caf082ef8609a6ac26159ce115f55ab7d00231a3" }, { "url": "https://git.kernel.org/stable/c/e3ccd4ecab09b22f507f49cb7ed9990c7158ceab" }, { "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" } } } }