CVE-2026-68155
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: libceph: Reject monmaps advertising zero monitors A message of type CEPH_MSG_MON_MAP contains a monmap that is sent from a monitor to the client. This monmap contains information about the existing monitors in the cluster. Currently, a monmap indicating that there are zero monitors in the cluster is treated as valid. However, it is impossible to have zero monitors in the cluster and still receive a valid monmap from a monitor. Therefore, such a monmap must be corrupted and should be treated as invalid. Furthermore, a monmap with a monitor count of zero can subsequently crash the client when attempting to open a session with a monitor in __open_session(). This happens because the "BUG_ON(monc->monmap->num_mon < 1)" assertion in pick_new_mon() is triggered. This patch extends a check in ceph_monmap_decode() to also reject arriving mon_maps with num_mon == 0 rather than only with num_mon > CEPH_MAX_MON. [ idryomov: drop "log output for unusual values of num_mon" part ]
Severity
HIGH
CVSS score
7.5
(v3.1)
Vulnerability status
Received
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-08-10 13:20:01.657000
Last modified
2026-10-19 21:17:55.503000
View original CVE JSON
{
"id": "CVE-2026-68155",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-08-10T13:20:01.657",
"lastModified": "2026-10-19T21:17:55.503",
"vulnStatus": "Received",
"cveTags": [],
"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 ]"
}
],
"affected": [
{
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"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"net/ceph/mon_client.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
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{
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{
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},
{
"version": "6.1.183",
"lessThanOrEqual": "6.1.*",
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"status": "unaffected"
},
{
"version": "6.6.148",
"lessThanOrEqual": "6.6.*",
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"status": "unaffected"
},
{
"version": "6.12.101",
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{
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{
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"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
}
],
"ssvcV203": [
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"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"timestamp": "2026-10-16T15:45:06.305922Z",
"id": "CVE-2026-68155",
"options": [
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},
{
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"version": "2.0.3"
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"value": "CWE-20"
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