CVE-2026-89540 (GCVE-0-2026-89540)
Vulnerability from cvelistv5 – Published: 2026-09-11 19:44 – Updated: 2026-10-19 08:48
VLAI
EPSS
VEX
Title
sunrpc: init gssp_lock before publishing proc entry
Summary
In the Linux kernel, the following vulnerability has been resolved:
sunrpc: init gssp_lock before publishing proc entry
create_use_gss_proxy_proc_entry() publishes /proc/net/rpc/use-gss-proxy
via proc_create_data() before init_gssp_clnt() runs mutex_init() on
sn->gssp_lock. Once the dentry is linked under proc_subdir_lock it is
immediately reachable from userspace, so a write that lands in the
window drives set_gssp_clnt() into mutex_lock() on a zero-initialized
struct mutex.
create_use_gss_proxy_proc_entry(net)
proc_create_data("use-gss-proxy", ...) /* dentry live */
init_gssp_clnt(sn)
mutex_init(&sn->gssp_lock) /* too late */
write_gssp()
set_gssp_clnt(net)
mutex_lock(&sn->gssp_lock) /* uninitialized */
gssp_rpc_create(...)
sn->gssp_clnt = clnt
mutex_unlock(&sn->gssp_lock)
The window spans only the two statements between proc_create_data()
returning and init_gssp_clnt(), so a writer reaches it only if the
registering thread is preempted there while another task is already
opening the freshly published file. register_pernet_subsys() runs in
preemptible context under pernet_ops_rwsem, so that preemption is
possible, and the window widens on auth_rpcgss module load, when the
proc entry is created for every live net namespace whose tasks are
already running. A writer that wins the race locks a zero-filled
struct mutex. On CONFIG_DEBUG_MUTEXES the missing magic value trips a
"lock used without init" splat; on a production kernel the fast path
acquires the lock via CMPXCHG(owner, 0, current). In the latter case
a second writer that arrives before init_gssp_clnt() re-zeroes owner
can enter set_gssp_clnt() concurrently, shut down the first writer's
clnt while it is still in use, and leak the loser's clnt.
Fix by initializing sn->gssp_lock in sunrpc_init_net() so its lifetime
matches the sunrpc_net it lives in. sn->gssp_clnt is already NULL from
the kzalloc that backs net_generic storage, so the lazy helper is no
longer needed; drop init_gssp_clnt(), its prototype, and the call from
create_use_gss_proxy_proc_entry(). sunrpc.ko is a build-time
dependency of auth_rpcgss.ko, so sunrpc_init_net() has always run on
every netns before any auth_gss pernet init can publish the proc
entry.
Severity
7.8 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-16 19:23 UTC
Assigner
References
8 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
030d794bf49855f5e2a9e8dfbfad34211d1eb08b , < 159a4fab7170badd6c4a553aef81cac079d6f4ee
(git)
Affected: 030d794bf49855f5e2a9e8dfbfad34211d1eb08b , < b3526ae3351968f6726bcbe25d8d09973ad79109 (git) Affected: 030d794bf49855f5e2a9e8dfbfad34211d1eb08b , < 7f5bcdc8da15077ebe846c2756a5a17741021410 (git) Affected: 030d794bf49855f5e2a9e8dfbfad34211d1eb08b , < 89c8e0733e8c46b7973503f15b1b31a8587d8030 (git) Affected: 030d794bf49855f5e2a9e8dfbfad34211d1eb08b , < f15b87521168c2a92cb1931f532cba422f856f01 (git) Affected: 030d794bf49855f5e2a9e8dfbfad34211d1eb08b , < edeefb111d6181a4aa278f415b005efe284b9489 (git) Affected: 030d794bf49855f5e2a9e8dfbfad34211d1eb08b , < 3f019571928b269feebcff59926ec13294215e0e (git) Affected: 030d794bf49855f5e2a9e8dfbfad34211d1eb08b , < 5ce1ed6159731a41fdd0b03eedbed4e147036a5a (git) |
guessed | |
| Linux | Linux |
Affected:
3.10
Unaffected: 0 , < 3.10 (semver) Unaffected: 5.10.270 , ≤ 5.10.* (semver) Unaffected: 5.15.221 , ≤ 5.15.* (semver) Unaffected: 6.1.188 , ≤ 6.1.* (semver) Unaffected: 6.6.157 , ≤ 6.6.* (semver) Unaffected: 6.12.109 , ≤ 6.12.* (semver) Unaffected: 6.18.50 , ≤ 6.18.* (semver) Unaffected: 7.2.4 , ≤ 7.2.* (semver) Unaffected: 7.3 , ≤ * (original_commit_for_fix) |
guessed |
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsunrpc: init gssp_lock before publishing proc entry\n\ncreate_use_gss_proxy_proc_entry() publishes /proc/net/rpc/use-gss-proxy\nvia proc_create_data() before init_gssp_clnt() runs mutex_init() on\nsn-\u003egssp_lock. Once the dentry is linked under proc_subdir_lock it is\nimmediately reachable from userspace, so a write that lands in the\nwindow drives set_gssp_clnt() into mutex_lock() on a zero-initialized\nstruct mutex.\n\n create_use_gss_proxy_proc_entry(net)\n proc_create_data(\"use-gss-proxy\", ...) /* dentry live */\n init_gssp_clnt(sn)\n mutex_init(\u0026sn-\u003egssp_lock) /* too late */\n\n write_gssp()\n set_gssp_clnt(net)\n mutex_lock(\u0026sn-\u003egssp_lock) /* uninitialized */\n gssp_rpc_create(...)\n sn-\u003egssp_clnt = clnt\n mutex_unlock(\u0026sn-\u003egssp_lock)\n\nThe window spans only the two statements between proc_create_data()\nreturning and init_gssp_clnt(), so a writer reaches it only if the\nregistering thread is preempted there while another task is already\nopening the freshly published file. register_pernet_subsys() runs in\npreemptible context under pernet_ops_rwsem, so that preemption is\npossible, and the window widens on auth_rpcgss module load, when the\nproc entry is created for every live net namespace whose tasks are\nalready running. A writer that wins the race locks a zero-filled\nstruct mutex. On CONFIG_DEBUG_MUTEXES the missing magic value trips a\n\"lock used without init\" splat; on a production kernel the fast path\nacquires the lock via CMPXCHG(owner, 0, current). In the latter case\na second writer that arrives before init_gssp_clnt() re-zeroes owner\ncan enter set_gssp_clnt() concurrently, shut down the first writer\u0027s\nclnt while it is still in use, and leak the loser\u0027s clnt.\n\nFix by initializing sn-\u003egssp_lock in sunrpc_init_net() so its lifetime\nmatches the sunrpc_net it lives in. sn-\u003egssp_clnt is already NULL from\nthe kzalloc that backs net_generic storage, so the lazy helper is no\nlonger needed; drop init_gssp_clnt(), its prototype, and the call from\ncreate_use_gss_proxy_proc_entry(). sunrpc.ko is a build-time\ndependency of auth_rpcgss.ko, so sunrpc_init_net() has always run on\nevery netns before any auth_gss pernet init can publish the proc\nentry."
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"version": "3.1"
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}
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsunrpc: init gssp_lock before publishing proc entry\n\ncreate_use_gss_proxy_proc_entry() publishes /proc/net/rpc/use-gss-proxy\nvia proc_create_data() before init_gssp_clnt() runs mutex_init() on\nsn-\u003egssp_lock. Once the dentry is linked under proc_subdir_lock it is\nimmediately reachable from userspace, so a write that lands in the\nwindow drives set_gssp_clnt() into mutex_lock() on a zero-initialized\nstruct mutex.\n\n create_use_gss_proxy_proc_entry(net)\n proc_create_data(\"use-gss-proxy\", ...) /* dentry live */\n init_gssp_clnt(sn)\n mutex_init(\u0026sn-\u003egssp_lock) /* too late */\n\n write_gssp()\n set_gssp_clnt(net)\n mutex_lock(\u0026sn-\u003egssp_lock) /* uninitialized */\n gssp_rpc_create(...)\n sn-\u003egssp_clnt = clnt\n mutex_unlock(\u0026sn-\u003egssp_lock)\n\nThe window spans only the two statements between proc_create_data()\nreturning and init_gssp_clnt(), so a writer reaches it only if the\nregistering thread is preempted there while another task is already\nopening the freshly published file. register_pernet_subsys() runs in\npreemptible context under pernet_ops_rwsem, so that preemption is\npossible, and the window widens on auth_rpcgss module load, when the\nproc entry is created for every live net namespace whose tasks are\nalready running. A writer that wins the race locks a zero-filled\nstruct mutex. On CONFIG_DEBUG_MUTEXES the missing magic value trips a\n\"lock used without init\" splat; on a production kernel the fast path\nacquires the lock via CMPXCHG(owner, 0, current). In the latter case\na second writer that arrives before init_gssp_clnt() re-zeroes owner\ncan enter set_gssp_clnt() concurrently, shut down the first writer\u0027s\nclnt while it is still in use, and leak the loser\u0027s clnt.\n\nFix by initializing sn-\u003egssp_lock in sunrpc_init_net() so its lifetime\nmatches the sunrpc_net it lives in. sn-\u003egssp_clnt is already NULL from\nthe kzalloc that backs net_generic storage, so the lazy helper is no\nlonger needed; drop init_gssp_clnt(), its prototype, and the call from\ncreate_use_gss_proxy_proc_entry(). sunrpc.ko is a build-time\ndependency of auth_rpcgss.ko, so sunrpc_init_net() has always run on\nevery netns before any auth_gss pernet init can publish the proc\nentry."
}
],
"id": "CVE-2026-89540",
"lastModified": "2026-10-19T09:17:48.820",
"metrics": {
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{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
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"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
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{
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{
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}
],
"role": "CISA Coordinator",
"timestamp": "2026-10-16T19:23:23.496498Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-09-11T20:19:37.097",
"references": [
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"url": "https://git.kernel.org/stable/c/159a4fab7170badd6c4a553aef81cac079d6f4ee"
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},
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},
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},
{
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{
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},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/edeefb111d6181a4aa278f415b005efe284b9489"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/f15b87521168c2a92cb1931f532cba422f856f01"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-10-23T04:06:19+00:00",
"cve": "CVE-2026-89540",
"id": "CVE-2026-89540",
"initial_release_date": "2026-09-11T00:00:00+00:00",
"product_status:known_affected": "278",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: sunrpc: init gssp_lock before publishing proc entry",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89540.json",
"version": "3"
},
"vulnrichment": {
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-89540",
"options": [
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"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-10-16T19:23:23.496498Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-10-16T19:23:24.509Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/sunrpc/auth_gss/gss_rpc_upcall.c",
"net/sunrpc/auth_gss/gss_rpc_upcall.h",
"net/sunrpc/auth_gss/svcauth_gss.c",
"net/sunrpc/sunrpc_syms.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "159a4fab7170badd6c4a553aef81cac079d6f4ee",
"status": "affected",
"version": "030d794bf49855f5e2a9e8dfbfad34211d1eb08b",
"versionType": "git"
},
{
"lessThan": "b3526ae3351968f6726bcbe25d8d09973ad79109",
"status": "affected",
"version": "030d794bf49855f5e2a9e8dfbfad34211d1eb08b",
"versionType": "git"
},
{
"lessThan": "7f5bcdc8da15077ebe846c2756a5a17741021410",
"status": "affected",
"version": "030d794bf49855f5e2a9e8dfbfad34211d1eb08b",
"versionType": "git"
},
{
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"status": "affected",
"version": "030d794bf49855f5e2a9e8dfbfad34211d1eb08b",
"versionType": "git"
},
{
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},
{
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},
{
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"status": "affected",
"version": "030d794bf49855f5e2a9e8dfbfad34211d1eb08b",
"versionType": "git"
},
{
"lessThan": "5ce1ed6159731a41fdd0b03eedbed4e147036a5a",
"status": "affected",
"version": "030d794bf49855f5e2a9e8dfbfad34211d1eb08b",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/sunrpc/auth_gss/gss_rpc_upcall.c",
"net/sunrpc/auth_gss/gss_rpc_upcall.h",
"net/sunrpc/auth_gss/svcauth_gss.c",
"net/sunrpc/sunrpc_syms.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "3.10"
},
{
"lessThan": "3.10",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.270",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.221",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "6.1.188",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "6.6.157",
"versionType": "semver"
},
{
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"version": "6.12.109",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "6.18.50",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "7.2.4",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix"
}
]
}
],
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"nodes": [
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsunrpc: init gssp_lock before publishing proc entry\n\ncreate_use_gss_proxy_proc_entry() publishes /proc/net/rpc/use-gss-proxy\nvia proc_create_data() before init_gssp_clnt() runs mutex_init() on\nsn-\u003egssp_lock. Once the dentry is linked under proc_subdir_lock it is\nimmediately reachable from userspace, so a write that lands in the\nwindow drives set_gssp_clnt() into mutex_lock() on a zero-initialized\nstruct mutex.\n\n create_use_gss_proxy_proc_entry(net)\n proc_create_data(\"use-gss-proxy\", ...) /* dentry live */\n init_gssp_clnt(sn)\n mutex_init(\u0026sn-\u003egssp_lock) /* too late */\n\n write_gssp()\n set_gssp_clnt(net)\n mutex_lock(\u0026sn-\u003egssp_lock) /* uninitialized */\n gssp_rpc_create(...)\n sn-\u003egssp_clnt = clnt\n mutex_unlock(\u0026sn-\u003egssp_lock)\n\nThe window spans only the two statements between proc_create_data()\nreturning and init_gssp_clnt(), so a writer reaches it only if the\nregistering thread is preempted there while another task is already\nopening the freshly published file. register_pernet_subsys() runs in\npreemptible context under pernet_ops_rwsem, so that preemption is\npossible, and the window widens on auth_rpcgss module load, when the\nproc entry is created for every live net namespace whose tasks are\nalready running. A writer that wins the race locks a zero-filled\nstruct mutex. On CONFIG_DEBUG_MUTEXES the missing magic value trips a\n\"lock used without init\" splat; on a production kernel the fast path\nacquires the lock via CMPXCHG(owner, 0, current). In the latter case\na second writer that arrives before init_gssp_clnt() re-zeroes owner\ncan enter set_gssp_clnt() concurrently, shut down the first writer\u0027s\nclnt while it is still in use, and leak the loser\u0027s clnt.\n\nFix by initializing sn-\u003egssp_lock in sunrpc_init_net() so its lifetime\nmatches the sunrpc_net it lives in. sn-\u003egssp_clnt is already NULL from\nthe kzalloc that backs net_generic storage, so the lazy helper is no\nlonger needed; drop init_gssp_clnt(), its prototype, and the call from\ncreate_use_gss_proxy_proc_entry(). sunrpc.ko is a build-time\ndependency of auth_rpcgss.ko, so sunrpc_init_net() has always run on\nevery netns before any auth_gss pernet init can publish the proc\nentry."
}
],
"metrics": [
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"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
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{
"lang": "en",
"value": "AV:L - The bug is reached only by write(2) to /proc/net/rpc/use-gss-proxy (write_gssp \u2192 set_gssp_clnt \u2192 mutex_lock(\u0026sn-\u003egssp_lock)); remote NFS/RPC peers never hit that procfs path.\nAC:L - The attacker fully controls writer threads that hammer the proc file, and on auth_rpcgss module load register_pernet_subsys() publishes it for every live netns whose tasks are already running; preemption between proc_create_data() and mutex_init() is possible in that preemptible pernet context, so the race is attacker-driven.\nPR:L - The 0600 use-gss-proxy entry inherits /proc/net ownership from proc_net_ns_init()\u0027s make_kuid(net-\u003euser_ns, 0), so an unprivileged user who unshares user+net namespaces owns the file; write_gssp() has no capable() check.\nUI:N - The attacker creates the namespace and writes \"1\" to the proc file from their own tasks; no victim must mount a filesystem, open a file, or otherwise cooperate.\nS:U - Uninitialized-mutex use and concurrent rpc_clnt teardown corrupt host kernel memory inside the same kernel security authority; this is not a VM escape, IOMMU bypass, or other cross-boundary impact.\nC:H - A writer that wins the race locks a zeroed mutex; mutex_init() can then re-zero owner so a second writer enters set_gssp_clnt() concurrently and rpc_shutdown_client()s a live rpc_clnt, a use-after-free that per kernel guidance yields an arbitrary read primitive.\nI:H - Concurrent set_gssp_clnt() can shut down an in-use rpc_clnt (UAF) while mutex_init() of a held lock corrupts mutex wait-list state, giving heap/lock-structure writes exploitable for control-flow hijack rather than a pure crash.\nA:H - CONFIG_DEBUG_MUTEXES treats the uninitialized lock as a lock-used-without-init splat/oops, and on production kernels the rpc_clnt UAF and corrupted mutex wait lists cause a kernel oops or panic."
}
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}
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Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
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.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.