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CVSS 9.8 · CRITICAL

CVE-2026-74581Memory corruption in Linux kernel IPv6 stack

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.

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Analysis

A critical vulnerability was found in the Linux kernel IPv6 routing stack. A stale pointer in the routing rule suppression logic can lead to a use-after-free condition, potentially allowing for system crashes or arbitrary code execution via network-triggered routing lookups.

Relevant roles

LinuxBackendCloudDockerKubernetesciberseguridad

Severity

Score: 9.8(CRITICAL)
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
AV: NETWORK
AC: LOW
PR: NONE
UI: NONE
S: UNCHANGED
C: HIGH
I: HIGH
A: HIGH

EPSS

Probability of exploitation (next 30 days): 0.0016 (0.2%)
Percentile: 5.8%
EPSS: 2026-08-24

Technical description

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.

Published: 8/21/2026, 5:16:44 PM
Last modified: 8/25/2026, 6:18:31 AM

References

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