net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels
In the Linux kernel, the following vulnerability has been resolved: net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels seg6_input_core() and rpl_input() call ip6_route_input() which sets a NOREF dst on the skb, then pass it to dst_cache_set_ip6() invoking dst_hold() unconditionally. On PREEMPT_RT, ksoftirqd is preemptible and a higher-priority task can release the underlying pcpu_rt between the lookup and the caching through a concurrent FIB lookup on a shared nexthop. Simplified race sequence: ksoftirqd/X higher-prio task (same CPU X) ----------- -------------------------------- seg6_input_core(,skb)/rpl_input(skb) dst_cache_get() -> miss ip6_route_input(skb) -> ip6_pol_route(,skb,flags) [RT6_LOOKUP_F_DST_NOREF in flags] -> FIB lookup resolves fib6_nh [nhid=N route] -> rt6_make_pcpu_route() [creates pcpu_rt, refcount=1] pcpu_rt->sernum = fib6_sernum [fib6_sernum=W] -> cmpxchg(fib6_nh.rt6i_pcpu, NULL, pcpu_rt) [slot was empty, store succeeds] -> skb_dst_set_noref(skb, dst) [dst is pcpu_rt, refcount still 1] rt_genid_bump_ipv6() -> bumps fib6_sernum [fib6_sernum from W to Z] ip6_route_output() -> ip6_pol_route() -> FIB lookup resolves fib6_nh [nhid=N] -> rt6_get_pcpu_route() pcpu_rt->sernum != fib6_sernum [W <> Z, stale] -> prev = xchg(rt6i_pcpu, NULL) -> dst_release(prev) [prev is pcpu_rt, refcount 1->0, dead] dst = skb_dst(skb) [dst is the dead pcpu_rt] dst_cache_set_ip6(dst) -> dst_hold() on dead dst -> WARN / use-after-free For the race to occur, ksoftirqd must be pree
CVE-2026-46099
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-46099
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "af4a2209b1344939eaac11f269c261d347cbc3ee",
"lessThan": "51fef5a7c4d160839199e941929456ba21ddf73c",
"versionType": "git"
},
{
"status": "affected",
"version": "af4a2209b1344939eaac11f269c261d347cbc3ee",
"lessThan": "b258b849a580285a1692e782ebc902b44c884a71",
"versionType": "git"
},
{
"status": "affected",
"version": "af4a2209b1344939eaac11f269c261d347cbc3ee",
"lessThan": "6bd17925bd6866027a6555db17905b9fc073d38d",
"versionType": "git"
},
{
"status": "affected",
"version": "af4a2209b1344939eaac11f269c261d347cbc3ee",
"lessThan": "52f9db67f8f35f436366cf4980b4f0a2583d0ef0",
"versionType": "git"
},
{
"status": "affected",
"version": "af4a2209b1344939eaac11f269c261d347cbc3ee",
"lessThan": "b778b6d095421619c331fd2d7751143cd5387103",
"versionType": "git"
},
{
"status": "affected",
"version": "af4a2209b1344939eaac11f269c261d347cbc3ee",
"lessThan": "9dd5481f960e337b81d7dfe429529495c1c481c0",
"versionType": "git"
},
{
"status": "affected",
"version": "af4a2209b1344939eaac11f269c261d347cbc3ee",
"lessThan": "f9c52a6ba9780bd27e0bf4c044fd91c13c778b6e",
"versionType": "git"
}
],
"programFiles": [
"net/ipv6/rpl_iptunnel.c",
"net/ipv6/seg6_iptunnel.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.12"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.12",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.15.209",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.175",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.140",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.86",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.27",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.0.4",
"versionType": "semver",
"lessThanOrEqual": "7.0.*"
},
{
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/ipv6/rpl_iptunnel.c",
"net/ipv6/seg6_iptunnel.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-46099
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #40116 · Revision 1
- Added to Heist Feed
- Publisher date