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Echo: linux: security update to 6.1.176-1

high Tenable Cloud Security Plugin ID 457569

Description

There are packages installed that are affected by a vulnerability referenced in the following CVE:

 - 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 preemptible (PREEMPT_RT without
 PREEMPT_RT_NEEDS_BH_LOCK) and a concurrent task must be able to release the pcpu_rt. Shared nexthop
 objects provide such a path, as two routes pointing to the same nhid share the same fib6_nh and its
 rt6i_pcpu entry. Fix seg6_input_core() and rpl_input() by calling skb_dst_force() after ip6_route_input()
 to force the NOREF dst into a refcounted one before caching. The output path is not affected as
 ip6_route_output() already returns a refcounted dst. (CVE-2026-46099)

Solution

Update the linux library and its related packages to version 6.1.176-1 or later.

See Also

https://advisory.echohq.com/cve/CVE-2026-46099

Plugin Details

Severity: High

ID: 457569

Version: Revision 1.1

Type: Local

Published: 10/2/2026

Updated: 10/2/2026

Risk Information

VPR

Risk Factor: Medium

Score: 4.5

Percentile: 57.6

CVSS v2

Risk Factor: High

Base Score: 7.6

Temporal Score: 5.6

Vector: CVSS2#AV:N/AC:H/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2026-46099

CVSS v3

Risk Factor: High

Base Score: 7.3

Temporal Score: 6.4

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

Exploit Ease: No known exploits are available

Patch Publication Date: 5/28/2026

Vulnerability Publication Date: 5/26/2026

Reference Information

CVE: CVE-2026-46099