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TI-2026-45574 Aliases CVE-2026-64009GHSA-666q-fgc6-3x4w

xfrm: Check for underflow in xfrm_state_mtu

Priority LOW 35CWE-191Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Partial Red Hat: 16 fixed, 3 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-191 and the CVSS impact.

Summary

In the Linux kernel, the following vulnerability has been resolved: xfrm: Check for underflow in xfrm_state_mtu Leo Lin reported OOB write issue in esp component: xfrm_state_mtu() returns u32 but performs its arithmetic in unsigned modulo-2^32 space using an attacker-influenced "header_len + authsize + net_adj" subtracted from a small "mtu" argument. A nobody user can install an IPv4 ESP tunnel SA with a large authentication key (XFRMA_ALG_AUTH_TRUNC, e.g. hmac(sha512), 64-byte key, 64-byte trunc), configure a small interface MTU (68 bytes), and set XFRMA_TFCPAD to a large value. When a single UDP datagram is then sent through the tunnel, xfrm_state_mtu() underflows to a near-2^32 value, and esp_output() consumes it as a signed int via: padto = min(x->tfcpad, xfrm_state_mtu(x, mtu_cached)) esp.tfclen = padto - skb->len (assigned to int) esp.tfclen ends up negative (e.g. -207). It is sign-extended to size_t when passed to memset() inside esp_output_fill_trailer(), producing a ~16 EB write of zeroes at skb_tail_pointer(skb). KASAN logs it as "Write of size 18446744073709551537 at addr ffff888...". Check for underflow and return 1. This causes the sendmsg attempt to fail with ENETUNREACH.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00144 3rd percentileScored 2026-11-07
Fix Partial Linux (Linux): 5.10.259, 5.15.210, 6.1.176 +5Red Hat: 4 advisoriesRed Hat: 16 fixed, 3 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

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

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux2.6.22 and later5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.93, 6.18.35, 7.0.12, 7.1Patch availableCNA
  • Linux VendorLinux Affected 2.6.22 and later Fixed in 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.93, 6.18.35, 7.0.12, 7.1 Patch available CNA

CPE configurations NVD · 6

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*2.6.22 to before 5.10.259; 5.11 to before 5.15.210; 5.16 to before 6.1.176; 6.2 to before 6.6.143; 6.7 to before 6.12.93; 6.13 to before 6.18.35; 6.19 to before 7.0.12VulnerableLinux
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:7.1:rc5:*:*:*:*:*:*7.1 rc5VulnerableLinux
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 2.6.22 to before 5.10.259; 5.11 to before 5.15.210; 5.16 to before 6.1.176; 6.2 to before 6.6.143; 6.7 to before 6.12.93; 6.13 to before 6.18.35; 6.19 to before 7.0.12 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
  • cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:* Versions 7.1 rc5 Vulnerable ·Linux

Remediation

  • Fix · CNA Linux (Linux) Fixed in 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.93, 6.18.35, 7.0.12, 7.1

Red Hat 4 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-2026:85773 Released 2026-10-20 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • Red Hat Enterprise Linux BaseOS (v. 8) bpftool-4.18.0-553.176.1.el8_10, kernel-4.18.0-553.176.1.el8_10, kernel-abi-stablelists-4.18.0-553.176.1.el8_10 +19
    • Red Hat Enterprise Linux CRB (v. 8) kernel-tools-libs-devel-4.18.0-553.176.1.el8_10
  • RHSA-2026:85774 Released 2026-10-20 · Red Hat rating Important
    kernel-rt security, bug fix, and enhancement update
    • Red Hat Enterprise Linux NFV (v. 8) kernel-rt-4.18.0-553.176.1.rt7.517.el8_10, kernel-rt-core-4.18.0-553.176.1.rt7.517.el8_10, kernel-rt-debug-4.18.0-553.176.1.rt7.517.el8_10 +9
    • Red Hat Enterprise Linux RT (v. 8) kernel-rt-4.18.0-553.176.1.rt7.517.el8_10, kernel-rt-core-4.18.0-553.176.1.rt7.517.el8_10, kernel-rt-debug-4.18.0-553.176.1.rt7.517.el8_10 +7
Show 1 more Red Hat advisories
  • RHSA-2026:85321 Released 2026-10-19 · Red Hat rating Important
    kernel security, bug fix, and enhancement update
    • 10Base-SMTV kernel-modules-internal-6.12.0-211.67.1.el10_2
    • Red Hat Enterprise Linux AppStream (v. 10) kernel-64k-debug-devel-6.12.0-211.67.1.el10_2, kernel-64k-debug-devel-matched-6.12.0-211.67.1.el10_2, kernel-64k-devel-6.12.0-211.67.1.el10_2 +12
    • Red Hat Enterprise Linux BaseOS (v. 10) kernel-6.12.0-211.67.1.el10_2, kernel-64k-6.12.0-211.67.1.el10_2, kernel-64k-core-6.12.0-211.67.1.el10_2 +29
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) kernel-tools-libs-devel-6.12.0-211.67.1.el10_2, libperf-6.12.0-211.67.1.el10_2
    • Red Hat Enterprise Linux Hidden (v. 10) kernel-modules-internal-6.12.0-211.67.1.el10_2
    • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt-6.12.0-211.67.1.el10_2, kernel-rt-64k-6.12.0-211.67.1.el10_2, kernel-rt-64k-core-6.12.0-211.67.1.el10_2 +21
    • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt-6.12.0-211.67.1.el10_2, kernel-rt-core-6.12.0-211.67.1.el10_2, kernel-rt-debug-6.12.0-211.67.1.el10_2 +9

Vendor assessments

Red Hat

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

ProductStatusPlan or fix
Red Hat Enterprise Linux 6Affected—
Red Hat Enterprise Linux 7AffectedNo fix yet
Red Hat Enterprise Linux 9AffectedNo fix yet
10Base-SMTVFixed RHSA-2026:85321
Red Hat Enterprise Linux AppStream (v. 10)Fixed RHSA-2026:85321
Red Hat Enterprise Linux AppStream (v. 9)Fixed RHSA-2026:86033
Red Hat Enterprise Linux BaseOS (v. 10)Fixed RHSA-2026:85321
Red Hat Enterprise Linux BaseOS (v. 8)Fixed RHSA-2026:85773
Red Hat Enterprise Linux BaseOS (v. 9)Fixed RHSA-2026:86033
Red Hat Enterprise Linux CRB (v. 8)Fixed RHSA-2026:85773
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)Fixed RHSA-2026:85321
Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)Fixed RHSA-2026:86033
Red Hat Enterprise Linux Hidden (v. 10)Fixed RHSA-2026:85321
Red Hat Enterprise Linux NFV (v. 8)Fixed RHSA-2026:85774
Red Hat Enterprise Linux RT (v. 8)Fixed RHSA-2026:85774
Red Hat Enterprise Linux Real Time (v. 10)Fixed RHSA-2026:85321
Red Hat Enterprise Linux Real Time (v. 9)Fixed RHSA-2026:86033
Red Hat Enterprise Linux Real Time for NFV (v. 10)Fixed RHSA-2026:85321
Red Hat Enterprise Linux Real Time for NFV (v. 9)Fixed RHSA-2026:86033

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-64009
  2. 2026-10-03 Alias added: GHSA-666q-fgc6-3x4w
  3. 2026-10-13 Affected versions changed · Red Hat
  4. 2026-10-13 Weakness changed · NVD
  5. 2026-10-16 CISA SSVC decision points changed
  6. 2026-10-19 Weakness changed · CISA ADP
  7. 2026-11-05 Fix available: 10Base-SMTV, Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux AppStream (v. 9) +13 · Red Hat
  8. 2026-11-06 Fix available: RHSA-2026:85321 · Red Hat
  9. 2026-11-06 Fix available: RHSA-2026:86033 · Red Hat
  10. 2026-11-06 Fix available: RHSA-2026:85774 · Red Hat
  11. 2026-11-06 Fix available: RHSA-2026:85773 · Red Hat

References

Patch 8

  • 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