UnratedFix available
xorg-x11-server: Fix of 5 CVEs
Type: advisorySources: OSV
- CVE-2026-50257: fix use-after-free in miSyncDestroyFence() when a fence is destroyed while an Await group still references it - CVE-2026-50258: fix stack buffer overflow in XKB CheckKeyTypes() by rejecting key types whose numLevels exceeds XkbMaxShiftLevel - CVE-2026-50259: fix stack buffer overflow in XKB CheckKeyTypes() by clamping nMaps to the mapWidths buffer size - CVE-2026-50260: fix use-after-free in FreeCounter() when a SyncCounter is destroyed while an Await group still references it - CVE-2026-50261: fix use-after-free in SyncChangeCounter() by restarting trigger list iteration after a trigger fires
- Products
- xorg-x11-server-Xdmx, xorg-x11-server-Xephyr, xorg-x11-server-Xnest, xorg-x11-server-Xorg, xorg-x11-server-Xvfb, xorg-x11-server-Xwayland, xorg-x11-server-common, xorg-x11-server-devel, xorg-x11-server-source
- Affected versions
- Not specified
- Fixed versions
- 1.20.4-99.el7_9.tuxcare.els11
- CVEs
- CVE-2026-50257, CVE-2026-50258, CVE-2026-50259, CVE-2026-50260, CVE-2026-50261
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 11:36 UTC · Revision 1
Source evidence
- CVE-2026-50257: fix use-after-free in miSyncDestroyFence() when a fence is destroyed while an Await group still references it - CVE-2026-50258: fix stack buffer overflow in XKB CheckKeyTypes() by rejecting key types whose numLevels exceeds XkbMaxShiftLevel - CVE-2026-50259: fix stack buffer overflow in XKB CheckKeyTypes() by clamping nMaps to the mapWidths buffer size - CVE-2026-50260: fix use-after-free in FreeCounter() when a SyncCounter is destroyed while an Await group still references it - CVE-2026-50261: fix use-after-free in SyncChangeCounter() by restarting trigger list iteration after a trigger fires
osv:CLSA-2026-1788373494
xorg-x11-server-Xdmx
Fixed versions: 1.20.4-99.el7_9.tuxcare.els11
xorg-x11-server-Xephyr
Fixed versions: 1.20.4-99.el7_9.tuxcare.els11
xorg-x11-server-Xnest
Fixed versions: 1.20.4-99.el7_9.tuxcare.els11
xorg-x11-server-Xorg
Fixed versions: 1.20.4-99.el7_9.tuxcare.els11
xorg-x11-server-Xvfb
Fixed versions: 1.20.4-99.el7_9.tuxcare.els11
xorg-x11-server-Xwayland
Fixed versions: 1.20.4-99.el7_9.tuxcare.els11
xorg-x11-server-common
Fixed versions: 1.20.4-99.el7_9.tuxcare.els11
xorg-x11-server-devel
Fixed versions: 1.20.4-99.el7_9.tuxcare.els11
xorg-x11-server-source
Fixed versions: 1.20.4-99.el7_9.tuxcare.els11
Complete source record
{
"id": "69fec2d7e9b5894438ba3bfecad29a9fa885b3ebcfa37eefe47d4ce066c9e27a",
"url": "https://osv.dev/vulnerability/CLSA-2026-1788373494",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "xorg-x11-server: Fix of 5 CVEs",
"summary": "- CVE-2026-50257: fix use-after-free in miSyncDestroyFence() when a fence is destroyed while an Await group still references it - CVE-2026-50258: fix stack buffer overflow in XKB CheckKeyTypes() by rejecting key types whose numLevels exceeds XkbMaxShiftLevel - CVE-2026-50259: fix stack buffer overflow in XKB CheckKeyTypes() by clamping nMaps to the mapWidths buffer size - CVE-2026-50260: fix use-after-free in FreeCounter() when a SyncCounter is destroyed while an Await group still references it - CVE-2026-50261: fix use-after-free in SyncChangeCounter() by restarting trigger list iteration after a trigger fires",
"evidence": "osv:CLSA-2026-1788373494",
"products": [
{
"name": {
"value": "xorg-x11-server-Xdmx",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1.20.4-99.el7_9.tuxcare.els11",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xorg-x11-server-Xephyr",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1.20.4-99.el7_9.tuxcare.els11",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": []
},
{
"name": {
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"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1.20.4-99.el7_9.tuxcare.els11",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xorg-x11-server-Xorg",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
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"evidence": "/affected/3/ranges"
}
],
"affected_versions": []
},
{
"name": {
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"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1.20.4-99.el7_9.tuxcare.els11",
"evidence": "/affected/4/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xorg-x11-server-Xwayland",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1.20.4-99.el7_9.tuxcare.els11",
"evidence": "/affected/5/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xorg-x11-server-common",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1.20.4-99.el7_9.tuxcare.els11",
"evidence": "/affected/6/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xorg-x11-server-devel",
"evidence": "/affected/7/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
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"evidence": "/affected/7/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xorg-x11-server-source",
"evidence": "/affected/8/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1.20.4-99.el7_9.tuxcare.els11",
"evidence": "/affected/8/ranges"
}
],
"affected_versions": []
}
],
"severity": "unknown",
"structured": {
"id": "CLSA-2026-1788373494",
"aliases": [
"CLSA-2026-1788373494"
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.20.4-99.el7_9.tuxcare.els11"
}
]
}
],
"package": {
"name": "xorg-x11-server-Xdmx",
"purl": "pkg:rpm/tuxcare/xorg-x11-server-Xdmx?distro=rhel-7",
"ecosystem": "TuxCare:RHEL:7"
},
"database_specific": {
"source": "https://github.com/cloudlinux/tuxcare-osv/tree/main/data/els_os/rhel7els/CLSA-2026-1788373494.json"
}
},
{
"ranges": [
{
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{
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}
]
}
],
"package": {
"name": "xorg-x11-server-Xephyr",
"purl": "pkg:rpm/tuxcare/xorg-x11-server-Xephyr?distro=rhel-7",
"ecosystem": "TuxCare:RHEL:7"
},
"database_specific": {
"source": "https://github.com/cloudlinux/tuxcare-osv/tree/main/data/els_os/rhel7els/CLSA-2026-1788373494.json"
}
},
{
"ranges": [
{
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{
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},
{
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}
]
}
],
"package": {
"name": "xorg-x11-server-Xnest",
"purl": "pkg:rpm/tuxcare/xorg-x11-server-Xnest?distro=rhel-7",
"ecosystem": "TuxCare:RHEL:7"
},
"database_specific": {
"source": "https://github.com/cloudlinux/tuxcare-osv/tree/main/data/els_os/rhel7els/CLSA-2026-1788373494.json"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.20.4-99.el7_9.tuxcare.els11"
}
]
}
],
"package": {
"name": "xorg-x11-server-Xorg",
"purl": "pkg:rpm/tuxcare/xorg-x11-server-Xorg?distro=rhel-7",
"ecosystem": "TuxCare:RHEL:7"
},
"database_specific": {
"source": "https://github.com/cloudlinux/tuxcare-osv/tree/main/data/els_os/rhel7els/CLSA-2026-1788373494.json"
}
},
{
"ranges": [
{
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{
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],
"package": {
"name": "xorg-x11-server-Xvfb",
"purl": "pkg:rpm/tuxcare/xorg-x11-server-Xvfb?distro=rhel-7",
"ecosystem": "TuxCare:RHEL:7"
},
"database_specific": {
"source": "https://github.com/cloudlinux/tuxcare-osv/tree/main/data/els_os/rhel7els/CLSA-2026-1788373494.json"
}
},
{
"ranges": [
{
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},
{
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}
]
}
],
"package": {
"name": "xorg-x11-server-Xwayland",
"purl": "pkg:rpm/tuxcare/xorg-x11-server-Xwayland?distro=rhel-7",
"ecosystem": "TuxCare:RHEL:7"
},
"database_specific": {
"source": "https://github.com/cloudlinux/tuxcare-osv/tree/main/data/els_os/rhel7els/CLSA-2026-1788373494.json"
}
},
{
"ranges": [
{
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},
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}
]
}
],
"package": {
"name": "xorg-x11-server-common",
"purl": "pkg:rpm/tuxcare/xorg-x11-server-common?distro=rhel-7",
"ecosystem": "TuxCare:RHEL:7"
},
"database_specific": {
"source": "https://github.com/cloudlinux/tuxcare-osv/tree/main/data/els_os/rhel7els/CLSA-2026-1788373494.json"
}
},
{
"ranges": [
{
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"events": [
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},
{
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}
]
}
],
"package": {
"name": "xorg-x11-server-devel",
"purl": "pkg:rpm/tuxcare/xorg-x11-server-devel?distro=rhel-7",
"ecosystem": "TuxCare:RHEL:7"
},
"database_specific": {
"source": "https://github.com/cloudlinux/tuxcare-osv/tree/main/data/els_os/rhel7els/CLSA-2026-1788373494.json"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.20.4-99.el7_9.tuxcare.els11"
}
]
}
],
"package": {
"name": "xorg-x11-server-source",
"purl": "pkg:rpm/tuxcare/xorg-x11-server-source?distro=rhel-7",
"ecosystem": "TuxCare:RHEL:7"
},
"database_specific": {
"source": "https://github.com/cloudlinux/tuxcare-osv/tree/main/data/els_os/rhel7els/CLSA-2026-1788373494.json"
}
}
],
"modified": "2026-10-26T09:31:58.731757428Z",
"provider": "osv",
"upstream": [
"CVE-2026-50257",
"CVE-2026-50258",
"CVE-2026-50259",
"CVE-2026-50260",
"CVE-2026-50261"
],
"references": [
"https://errata.tuxcare.com/els_os/rhel7els/CLSA-2026-1788373494.html",
"https://nvd.nist.gov/vuln/detail/CVE-2026-50257",
"https://nvd.nist.gov/vuln/detail/CVE-2026-50258",
"https://nvd.nist.gov/vuln/detail/CVE-2026-50259",
"https://nvd.nist.gov/vuln/detail/CVE-2026-50260",
"https://nvd.nist.gov/vuln/detail/CVE-2026-50261"
]
},
"related_cves": [
{
"value": "CVE-2026-50257",
"evidence": "/upstream"
},
{
"value": "CVE-2026-50258",
"evidence": "/upstream"
},
{
"value": "CVE-2026-50259",
"evidence": "/upstream"
},
{
"value": "CVE-2026-50260",
"evidence": "/upstream"
},
{
"value": "CVE-2026-50261",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": null
},
"source_id": "core-osv",
"document_id": 449224,
"published_at": "2026-09-02T18:25:07+00:00"
}