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CVE-2026-98432

CRITICAL 9.8

Published 2026-10-15 · Last modified 2026-10-24

In the Linux kernel, the following vulnerability has been resolved: ipv4: free inet_opt and ireq_opt after an RCU grace period tcp_v4_syn_recv_sock() transfers ownership of ireq->ireq_opt to the child socket (newinet->inet_opt) without copying it. Another cpu can concurrently process a retransmitted SYN for the same request socket, and send a SYNACK from tcp_check_req(). tcp_v4_send_synack() and inet_csk_route_req() read ireq->ireq_opt under rcu_read_lock() only, and ip_build_and_send_pkt() and ip_options_build() then read opt->optlen twice. Note that the SYNACK timer itself is not an issue: it holds a reference on its request socket, and inet_csk_reqsk_queue_drop() calls timer_delete_sync() before the child can be freed. Since commit 079096f103fa ("tcp/dccp: install syn_recv requests into ehash table"), request sockets are processed without holding the listener lock, so nothing prevents the child socket from being freed while the SYNACK is still being built. TCP child sockets do not have SOCK_RCU_FREE, and inet_sock_destruct() frees inet_opt with a plain kfree(), leading to a use-after-free in ip_options_build(). A similar issue exists with request socket migration (net.ipv4.tcp_migrate_req=1, or a BPF_SK_REUSEPORT_SELECT_OR_MIGRATE program). reqsk_timer_handler() clones the request socket with inet_reqsk_clone(), so that the old request socket and its clone share the same ireq_opt, then reqsk_migrate_reset() clears the pointer in the old one. Another cpu holding a reference on the old request socket can still be using these options (sending a SYNACK, or creating a child in tcp_v4_syn_recv_sock()) when the clone is freed, and tcp_v4_reqsk_destructor() also uses a plain kfree(). Readers already use RCU, and other paths replacing inet_opt (do_ip_setsockopt(), cipso_v4_sock_setattr()...) already use kfree_rcu(). Use kfree_rcu() in inet_sock_destruct() and tcp_v4_reqsk_destructor() as well. IPv6 is not affected by the first issue, because tcp_v6_syn_recv_sock() duplicates the options. tcp_v6_reqsk_destructor() has the same migration issue with ipv6_opt, which is only set by CALIPSO. This will be addressed in a separate patch.

ELEVATED IMPACT

Severe if exploited (CVSS 9.8), but no known exploitation and low modeled probability. Patch on a normal cadence.

Exploitation likelihood

0.4%chance of exploitation in 30 days · 33rd percentile

○ In CISA KEV ○ Catalogued PoC

Impact if exploited

9.8CVSS 3.1 · CRITICAL

  • ConfidentialityHigh
  • IntegrityHigh
  • AvailabilityHigh

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ✓User interaction: No user interaction needed
  • ✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept

No public PoC is currently catalogued.

Search for new PoCs

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Data snapshot:

Affected

Vendors Linux

Products Linux

Weakness (CWE)

Not classified.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References and research data (JSON)

Vendor product assessments

Showing 32 of 278 vendor product statements; 246 omitted. Read the full vendor advisory.

  • kernel as a component of Red Hat Enterprise Linux 10 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/kernel

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
    • none available: Fix deferred
    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-debug as a component of Red Hat Enterprise Linux 10 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/kernel-debug

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
    • none available: Fix deferred
    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-rt as a component of Red Hat Enterprise Linux 10 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/kernel-rt

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
    • none available: Fix deferred
    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-rt-debug-kvm as a component of Red Hat Enterprise Linux 10 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/kernel-rt-debug-kvm

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
    • none available: Fix deferred
    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-zfcpdump-devel as a component of Red Hat Enterprise Linux 10 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/kernel-zfcpdump-devel

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
    • none available: Fix deferred
    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-doc as a component of Red Hat Enterprise Linux 6 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/kernel-doc

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
    • no fix planned: Out of support scope
    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-debug-modules as a component of Red Hat Enterprise Linux 8 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/kernel-debug-modules

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
    • none available: Fix deferred
    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-rt-debug-modules as a component of Red Hat Enterprise Linux 8 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/kernel-rt-debug-modules

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
    • none available: Fix deferred
    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-zfcpdump-modules as a component of Red Hat Enterprise Linux 8 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/kernel-zfcpdump-modules

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
    • none available: Fix deferred
    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-64k-debug-modules-extra as a component of Red Hat Enterprise Linux 9 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/kernel-64k-debug-modules-extra

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
    • none available: Fix deferred
    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-debug-modules as a component of Red Hat Enterprise Linux 9 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/kernel-debug-modules

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
    • none available: Fix deferred
    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-modules-partner as a component of Red Hat Enterprise Linux 9 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/kernel-modules-partner

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
    • none available: Fix deferred
    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-rt-64k-kvm as a component of Red Hat Enterprise Linux 9 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/kernel-rt-64k-kvm

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
    • none available: Fix deferred
    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-rt-devel as a component of Red Hat Enterprise Linux 9 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/kernel-rt-devel

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
    • none available: Fix deferred
    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-zfcpdump as a component of Red Hat Enterprise Linux 9 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/kernel-zfcpdump

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
    • none available: Fix deferred
    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • openshift/ose-rhel-coreos-9 as a component of Red Hat OpenShift Container Platform 4 · known affected

    Vendor assessment for this product only.

    pkg:oci/ose-rhel-coreos-9?repository_url=registry.redhat.io/openshift/ose-rhel-coreos-9

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
    • none available: Fix deferred
    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • bpftool as a component of Red Hat Enterprise Linux 7 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/bpftool

    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-abi-whitelists as a component of Red Hat Enterprise Linux 7 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/kernel-abi-whitelists

    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-debug as a component of Red Hat Enterprise Linux 7 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/kernel-debug

    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-debug-devel as a component of Red Hat Enterprise Linux 7 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/kernel-debug-devel

    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-doc as a component of Red Hat Enterprise Linux 7 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/kernel-doc

    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-kdump as a component of Red Hat Enterprise Linux 7 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/kernel-kdump

    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-rt as a component of Red Hat Enterprise Linux 7 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/kernel-rt

    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-rt-debug-devel as a component of Red Hat Enterprise Linux 7 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/kernel-rt-debug-devel

    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-rt-debug-kvm as a component of Red Hat Enterprise Linux 7 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/kernel-rt-debug-kvm

    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-rt-doc as a component of Red Hat Enterprise Linux 7 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/kernel-rt-doc

    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-rt-trace as a component of Red Hat Enterprise Linux 7 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/kernel-rt-trace

    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-rt-trace-kvm as a component of Red Hat Enterprise Linux 7 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/kernel-rt-trace-kvm

    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-tools as a component of Red Hat Enterprise Linux 7 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/kernel-tools

    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel-tools-libs as a component of Red Hat Enterprise Linux 7 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/kernel-tools-libs

    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • kernel.src as a component of Red Hat Enterprise Linux 7 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/kernel?arch=src

    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00
  • python-perf as a component of Red Hat Enterprise Linux 7 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/python-perf

    Red Hat · CVE-2026-98432 · Updated 2026-10-24T14:27:41+00:00

All CVSS metrics

  • CRITICAL 9.8 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
  • CRITICAL 9.8 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References

Advisories

Technical & other

Sources: NVD · CVE.org · EPSS