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TI-2026-55860 Aliases CVE-2026-80847GHSA-m3f3-9j4q-c4f2

tcp: clamp route advmss to TCP_MIN_MSS

Priority LOW 22Published · Updated

Key facts

Attack vector
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Privileges required
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User interaction
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Attack complexity
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Impact type
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Confidentiality · integrity · availability
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Fix status
Partial Red Hat: 7 without a fix

No CVSS vector from any source. Fix status from CNA and Red Hat.

Summary

In the Linux kernel, the following vulnerability has been resolved: tcp: clamp route advmss to TCP_MIN_MSS tcp_select_initial_window() assumes that callers never pass an MSS smaller than 1, but route-derived advmss values can violate that assumption. A too-small explicit RTAX_ADVMSS is one way to get there, but it is not the only one. The same divide-by-zero can also be reached through the "default advmss" path when RTAX_ADVMSS is left at 0 and the effective advmss is later driven down by route MTU and min_adv_mss. Introduce a tcp_dst_advmss() helper that clamps route advmss to TCP_MIN_MSS before TCP consumes it, and use it in the TCP paths that derive advmss from dst metrics. This keeps the effective MSS from dropping to zero before tcp_select_initial_window() rounds the receive window.

Why it matters now

EPSS 0.00213 11th percentileScored 2026-11-07
Fix Partial Linux (Linux): 6.1.191, 6.6.160, 6.12.111 +4Red Hat: 7 without a fix

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux2.6.12 and later6.1.191, 6.6.160, 6.12.111, 6.18.51, 7.1.13, 7.2.3, 7.3Patch availableCNA
  • Linux VendorLinux Affected 2.6.12 and later Fixed in 6.1.191, 6.6.160, 6.12.111, 6.18.51, 7.1.13, 7.2.3, 7.3 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*——Linux
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions — — ·Linux

Remediation

  • Fix · CNA Linux (Linux) Fixed in 6.1.191, 6.6.160, 6.12.111, 6.18.51, 7.1.13, 7.2.3, 7.3

Vendor assessments

Red Hat

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

ProductStatusPlan or fix
Red Hat Enterprise Linux 10AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 7AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 8AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 9AffectedNo fix yet: Fix deferred
Red Hat OpenShift Container Platform 4AffectedNo fix yet: Fix deferred
Red Hat OpenShift Container Platform 5AffectedNo fix yet: Fix deferred

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-80847
  2. 2026-10-03 Alias added: GHSA-m3f3-9j4q-c4f2
  3. 2026-10-19 Fix available: Linux/[email protected] · CNA
  4. 2026-10-21 Fix available: Linux/[email protected], Linux/Linux@788fbbf7d61f9742298417c207c91b6db159fbbc · CNA
  5. 2026-10-21 1 new reference · CNA
  6. 2026-10-30 Fix available: Linux/Linux@1aedef9ca04aad427a077c7c427ffd89768038bc, Linux/[email protected] · CNA
  7. 2026-10-30 1 new reference · CNA
  8. 2026-11-01 Affected versions changed · Red Hat
  9. 2026-11-01 CVSS score added · Red Hat

References

Other 7

  • 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-2021-02452 Incorrect authorization in Ubuntu linux kernel 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
See all 21741 →

Sources

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