CVE-2026-74581 (GCVE-0-2026-74581)
Vulnerability from cvelistv5
Published
2026-08-21 16:31
Modified
2026-08-25 05:40
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
net: ipv6: clear suppressed fib6 rule result
fib6_rule_suppress() drops a suppressed route with ip6_rt_put_flags(),
but leaves res->rt6 pointing at the released rt6_info.
If no later rule supplies a replacement, fib6_rule_lookup() still sees
res.rt6 and returns that stale dst to its caller. A suppressing rule can
therefore leak a released route back to rt6_lookup(), and the next put
hits rcuref_put_slowpath() from dst_release().
Clear res->rt6 when suppressing the route so suppressed lookups fall
through to the null dst instead of reusing the released one.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 209d35ee34e25f9668c404350a1c86d914c54ffa Version: 8ef8a76a340ebdb2c2eea3f6fb0ebbed09a16383 Version: cdef485217d30382f3bf6448c54b4401648fe3f1 Version: cdef485217d30382f3bf6448c54b4401648fe3f1 Version: cdef485217d30382f3bf6448c54b4401648fe3f1 Version: cdef485217d30382f3bf6448c54b4401648fe3f1 Version: cdef485217d30382f3bf6448c54b4401648fe3f1 Version: cdef485217d30382f3bf6448c54b4401648fe3f1 Version: ee38eb8cf9a7323884c2b8e0adbbeb2192d31e29 Version: 5.10.84 ≤ Version: 5.15.7 ≤ Version: 5.4.164 ≤ |
||
{
"containers": {
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"product": "Linux",
"programFiles": [
"net/ipv6/fib6_rules.c"
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{
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{
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{
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"status": "affected",
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"status": "affected",
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},
{
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"product": "Linux",
"programFiles": [
"net/ipv6/fib6_rules.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.16"
},
{
"lessThan": "5.16",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.265",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.216",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.183",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.151",
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"status": "unaffected",
"version": "6.12.103",
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},
{
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"status": "unaffected",
"version": "7.1.8",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
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"versionEndExcluding": "5.10.265",
"versionStartIncluding": "5.10.84",
"vulnerable": true
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{
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{
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{
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}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: clear suppressed fib6 rule result\n\nfib6_rule_suppress() drops a suppressed route with ip6_rt_put_flags(),\nbut leaves res-\u003ert6 pointing at the released rt6_info.\n\nIf no later rule supplies a replacement, fib6_rule_lookup() still sees\nres.rt6 and returns that stale dst to its caller. A suppressing rule can\ntherefore leak a released route back to rt6_lookup(), and the next put\nhits rcuref_put_slowpath() from dst_release().\n\nClear res-\u003ert6 when suppressing the route so suppressed lookups fall\nthrough to the null dst instead of reusing the released one."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - fib6_rule_suppress() runs on every IPv6 route lookup via fib6_rule_lookup(), including ip6_route_input() for received packets and icmp6/icmpv6 redirect handlers; WireGuard/VPN servers commonly deploy suppress_prefixlength rules (wg-quick), so remote IPv6 traffic to those hosts reaches the bug.\nAC:L - Once suppress_prefixlength IPv6 policy routing rules exist, any matching packet deterministically triggers fib6_rule_suppress() to release the route while leaving a stale res-\u003ert6 pointer; no race or uncontrollable memory layout is required.\nPR:N - Remote exploitation needs only the ability to send IPv6 packets through a host whose operator already configured suppress rules (e.g., wg-quick); CAP_NET_ADMIN is an admin deployment prerequisite, not attacker privilege on the target.\nUI:N - No victim action is required beyond normal delivery of attacker-generated IPv6 traffic (or ICMPv6 redirect) to a host performing policy-route lookup.\nS:U - The stale rt6_info/dst_entry UAF corrupts kernel heap memory within the same host security boundary; it is not a VM escape or cross-authority sandbox break.\nC:H - Returning a released rt6_info leaves a dangling dst_entry in ip6_dst_cache; subsequent reads through ip6_dst_idev(), dst metrics, or error paths are classic slab UAF with attacker-influencable heap reuse via sustained IPv6 traffic.\nI:H - Double-free/imbalanced rcuref put and post-free use of rt6_info fields give heap corruption primitives; UAF on dst/route cache objects is routinely leveraged for kernel write and control-flow hijack.\nA:H - Commit explicitly reports rcuref_put_slowpath() WARN from dst_release() on the freed route; UAF and refcount corruption can oops/panic the kernel, fully denying availability."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-25T05:40:07.594Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/90c57310e266eb94e4a80d6b15a9ca131d2e82cb"
},
{
"url": "https://git.kernel.org/stable/c/5d29b286c9de0b309e94b9ed083aa1a2f429434f"
},
{
"url": "https://git.kernel.org/stable/c/354db6243eca59e9d187ffbf8b7955b044ce84dc"
},
{
"url": "https://git.kernel.org/stable/c/6d98c70fe0ba8c7708bfd5b2a5174d2086775daa"
},
{
"url": "https://git.kernel.org/stable/c/9bad152c42b37499162367fe47867411e62fffa3"
},
{
"url": "https://git.kernel.org/stable/c/dc3ab04220667f254f4348572b2a0b3febff89fb"
},
{
"url": "https://git.kernel.org/stable/c/a341c091ca0bfae377747b1b59a3bd8ebe18a937"
},
{
"url": "https://git.kernel.org/stable/c/6aea62e433fe1b586202a5fee8b5807ce635e1d7"
}
],
"title": "net: ipv6: clear suppressed fib6 rule result",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74581",
"datePublished": "2026-08-21T16:31:54.683Z",
"dateReserved": "2026-08-15T05:44:03.918Z",
"dateUpdated": "2026-08-25T05:40:07.594Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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