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TI-2026-45589 Aliases CVE-2026-64024GHSA-h337-654q-329c

tcp: fix stale per-CPU tcp_tw_isn leak enabling ISN prediction

Priority MEDIUM 46CWE-362Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
Low · High · High
Fix status
Partial Red Hat: 12 fixed, 1 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-401.

Summary

In the Linux kernel, the following vulnerability has been resolved: tcp: fix stale per-CPU tcp_tw_isn leak enabling ISN prediction Blamed commit moved the TIME_WAIT-derived ISN from the skb control block to a per-CPU variable, assuming the value would always be consumed by tcp_conn_request() for the same packet that wrote it. That assumption is violated by multiple drop paths between the producer (__this_cpu_write(tcp_tw_isn, isn) in tcp_v{4,6}_rcv()) and the consumer (tcp_conn_request()): - min_ttl / min_hopcount check - xfrm policy check - tcp_inbound_hash() MD5/AO mismatch - tcp_filter() eBPF/SO_ATTACH_FILTER drop - th->syn && th->fin discard in tcp_rcv_state_process() TCP_LISTEN - psp_sk_rx_policy_check() in tcp_v{4,6}_do_rcv() - tcp_checksum_complete() in tcp_v{4,6}_do_rcv() - tcp_v{4,6}_cookie_check() returning NULL When a packet is dropped on any of these paths, tcp_tw_isn is left set. The next SYN processed on the same CPU then consumes the non zero value in tcp_conn_request(), receiving a potentially predictable ISN. This patch moves back tcp_tw_isn to skb->cb[], getting rid of the per-cpu variable. Note that tcp_v{4,6}_fill_cb() do not set it. Very litle impact on overall code size/complexity: $ scripts/bloat-o-meter -t vmlinux.old vmlinux.new add/remove: 0/0 grow/shrink: 2/1 up/down: 8/-15 (-7) Function old new delta tcp_v6_rcv 3038 3042 +4 tcp_v4_rcv 3035 3039 +4 tcp_conn_request 2938 2923 -15 Total: Before=24436060, After=24436053, chg -0.00%

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00308 23rd percentileScored 2026-11-07
Fix Partial Linux (Linux): 6.12.114, 6.18.34, 7.0.11 +1Red Hat: 2 advisoriesRed Hat: 12 fixed, 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux6.10 and later6.12.114, 6.18.34, 7.0.11, 7.1Patch availableCNA
  • Linux VendorLinux Affected 6.10 and later Fixed in 6.12.114, 6.18.34, 7.0.11, 7.1 Patch available CNA

CPE configurations NVD · 5

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*6.10 to before 6.12.114; 6.13 to before 6.18.34; 6.19 to before 7.0.11VulnerableLinux
cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*7.1 rc1VulnerableLinux
cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:*7.1 rc2VulnerableLinux
cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:*7.1 rc3VulnerableLinux
cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:*7.1 rc4VulnerableLinux
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 6.10 to before 6.12.114; 6.13 to before 6.18.34; 6.19 to before 7.0.11 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* Versions 7.1 rc1 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* Versions 7.1 rc2 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:* Versions 7.1 rc3 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:* Versions 7.1 rc4 Vulnerable ·Linux

Remediation

  • Fix · CNA Linux (Linux) Fixed in 6.12.114, 6.18.34, 7.0.11, 7.1

Red Hat 2 advisories

  • RHSA-2026:86033 Released 2026-10-20 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • Red Hat Enterprise Linux AppStream (v. 9) kernel-64k-debug-devel-5.14.0-687.59.1.el9_8, kernel-64k-debug-devel-matched-5.14.0-687.59.1.el9_8, kernel-64k-devel-5.14.0-687.59.1.el9_8 +12
    • Red Hat Enterprise Linux BaseOS (v. 9) kernel-5.14.0-687.59.1.el9_8, kernel-64k-5.14.0-687.59.1.el9_8, kernel-64k-core-5.14.0-687.59.1.el9_8 +28
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) kernel-tools-libs-devel-5.14.0-687.59.1.el9_8, libperf-5.14.0-687.59.1.el9_8
    • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt-5.14.0-687.59.1.el9_8, kernel-rt-64k-5.14.0-687.59.1.el9_8, kernel-rt-64k-core-5.14.0-687.59.1.el9_8 +21
    • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt-5.14.0-687.59.1.el9_8, kernel-rt-core-5.14.0-687.59.1.el9_8, kernel-rt-debug-5.14.0-687.59.1.el9_8 +9
  • RHSA-2026:76738 Released 2026-10-08 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • 10Base-SMTV kernel-modules-internal-6.12.0-211.63.1.el10_2
    • Red Hat Enterprise Linux AppStream (v. 10) kernel-64k-debug-devel-6.12.0-211.63.1.el10_2, kernel-64k-debug-devel-matched-6.12.0-211.63.1.el10_2, kernel-64k-devel-6.12.0-211.63.1.el10_2 +12
    • Red Hat Enterprise Linux BaseOS (v. 10) kernel-6.12.0-211.63.1.el10_2, kernel-64k-6.12.0-211.63.1.el10_2, kernel-64k-core-6.12.0-211.63.1.el10_2 +29
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) kernel-tools-libs-devel-6.12.0-211.63.1.el10_2, libperf-6.12.0-211.63.1.el10_2
    • Red Hat Enterprise Linux Hidden (v. 10) kernel-modules-internal-6.12.0-211.63.1.el10_2
    • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt-6.12.0-211.63.1.el10_2, kernel-rt-64k-6.12.0-211.63.1.el10_2, kernel-rt-64k-core-6.12.0-211.63.1.el10_2 +21
    • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt-6.12.0-211.63.1.el10_2, kernel-rt-core-6.12.0-211.63.1.el10_2, kernel-rt-debug-6.12.0-211.63.1.el10_2 +9

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
10Base-SMTVFixed RHSA-2026:76738
Red Hat Enterprise Linux AppStream (v. 10)Fixed RHSA-2026:76738
Red Hat Enterprise Linux AppStream (v. 9)Fixed RHSA-2026:86033
Red Hat Enterprise Linux BaseOS (v. 10)Fixed RHSA-2026:76738
Red Hat Enterprise Linux BaseOS (v. 9)Fixed RHSA-2026:86033
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)Fixed RHSA-2026:76738
Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)Fixed RHSA-2026:86033
Red Hat Enterprise Linux Hidden (v. 10)Fixed RHSA-2026:76738
Red Hat Enterprise Linux Real Time (v. 10)Fixed RHSA-2026:76738
Red Hat Enterprise Linux Real Time (v. 9)Fixed RHSA-2026:86033
Red Hat Enterprise Linux Real Time for NFV (v. 10)Fixed RHSA-2026:76738
Red Hat Enterprise Linux Real Time for NFV (v. 9)Fixed RHSA-2026:86033
Not affected: 3 products
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-64024
  2. 2026-10-03 Alias added: GHSA-h337-654q-329c
  3. 2026-10-13 Weakness changed · NVD
  4. 2026-10-16 CISA SSVC decision points changed
  5. 2026-10-19 Weakness changed · CISA ADP
  6. 2026-10-21 Fix available: RHSA-2026:86033 · Red Hat
  7. 2026-10-21 Fix available: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) +2 · Red Hat
  8. 2026-10-21 Fix available: Linux/[email protected], Linux/Linux@8bb6aa419b142dcc2680177ecc39c4c38db7fc16 · CNA
  9. 2026-10-21 1 new reference · CNA
  10. 2026-10-26 Fix available: RHSA-2026:76738 · Red Hat
  11. 2026-10-26 Fix available: 10Base-SMTV, Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10) +4 · Red Hat
  12. 2026-10-29 Affected versions changed · Red Hat

References

Patch 4

  • TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
  • TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
  • TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
  • TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
  • TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
See all 15278 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences