MOKSHA-2026-0063 (moksha-2026-0063)
Vulnerability from moksha – Published: 2026-04-24 06:00 – Updated:
VLAI
Title
Negative kbps Injection in VIF.qos_algorithm_params
Summary
A vm-admin in XAPI-based hypervisors (XenServer, XCP-ng) can inject negative kbps values into VIF.qos_algorithm_params. XAPI parses via Int64.of_string without sign validation. xenopsd computes a negative bytes_per_interval which fails the >0L bounds check, silently dropping the rate limit. The XAPI database shows the negative value as the configured rate while no rate is enforced in xenstore, creating an observability gap for administrators and monitoring tools.
Severity
5.3 (Medium)
CWE
- CWE-20 - Improper Input Validation
References
1 reference
Impacted products
2 products
| Vendor | Product | Version | |
|---|---|---|---|
| Cloud Software Group | XenServer |
Affected:
all
(custom)
|
|
| Vates | XCP-ng |
Affected:
all
(custom)
|
Credits
{
"containers": {
"cna": {
"affected": [
{
"product": "XenServer",
"vendor": "Cloud Software Group",
"versions": [
{
"status": "affected",
"version": "all",
"versionType": "custom"
}
]
},
{
"product": "XCP-ng",
"vendor": "Vates",
"versions": [
{
"status": "affected",
"version": "all",
"versionType": "custom"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Jakob Wolffhechel, Moksha"
}
],
"descriptions": [
{
"lang": "en",
"value": "A vm-admin in XAPI-based hypervisors (XenServer, XCP-ng) can inject negative kbps values into VIF.qos_algorithm_params. XAPI parses via Int64.of_string without sign validation. xenopsd computes a negative bytes_per_interval which fails the \u003e0L bounds check, silently dropping the rate limit. The XAPI database shows the negative value as the configured rate while no rate is enforced in xenstore, creating an observability gap for administrators and monitoring tools."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 5.3,
"baseSeverity": "MEDIUM",
"vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N",
"version": "3.1"
},
"format": "CVSS"
},
{
"cvssV4_0": {
"baseScore": 5.3,
"baseSeverity": "MEDIUM",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
"version": "4.0"
},
"format": "CVSS"
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-20",
"description": "Improper Input Validation",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-04-24T06:00:00Z",
"orgId": "moksha.dk",
"shortName": "Moksha"
},
"references": [
{
"url": "https://cna.moksha.dk/MOKSHA-2026-0063"
}
],
"title": "Negative kbps Injection in VIF.qos_algorithm_params"
}
},
"cveMetadata": {
"alternateIds": [
"GCVE-117-2026-0063"
],
"assignerOrgId": "moksha.dk",
"cveId": "MOKSHA-2026-0063",
"datePublished": "2026-04-24T06:00:00Z",
"state": "PUBLISHED",
"x_moksha_note": "Self-issued advisory. MOKSHA-2026-NNNN is not a MITRE CVE ID. Schema follows CVE JSON 5.1 for tooling compatibility. alternateIds contains GCVE cross-references (GNA #117) and will also carry MITRE CVE IDs if assigned."
},
"dataType": "CVE_RECORD",
"dataVersion": "5.1"
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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