Read the docs
TI-2026-75677 Aliases CVE-2026-98549GHSA-p59j-fj4g-255h

Linux kernel TCP retransmission merges data across encryption boundary

Priority MEDIUM 40Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · None · High
Fix status
Partial Red Hat: 6 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.

Summary

The Linux kernel TCP retransmission queue can merge a socket buffer queued before a switch to device encryption with one queued after it. Merged data is then retransmitted in cleartext by PSP, or TLS device offload connections stall because drivers drop the merged buffer. The flaw can be reached over the network without privileges or user interaction and affects confidentiality and availability.

Written with Claude Haiku 5.5 from the sources below · 2026-11-05

Description from the CNA

In the Linux kernel, the following vulnerability has been resolved: tcp: prevent collapsing skbs across boundary in rtx queue tcp_write_collapse_fence() sets TCP_SKB_CB(skb)->eor = 1 on tcp_write_queue_tail(sk) to prevent skbs queued after a switch to device encryption from being collapsed into earlier skbs. The fence is a no-op if all earlier data has already been transmitted when the switch happens: sk->sk_write_queue is empty. The not yet acknowledged earlier skbs wait in sk->tcp_rtx_queue with eor 0. On a subsequent retransmit or SACK shift, tcp_retrans_try_collapse() or tcp_shift_skb_data() can then merge an skb queued after the switch into one queued before it. Both users of the fence are affected: - psp: devices only encrypt skbs with skb->decrypted set. The merged skb keeps decrypted = 0 from the earlier skb, so merged data sent after psp_sock_assoc_set_tx() is retransmitted in cleartext. - tls device offload: the merged skb straddles the start marker set in tls_set_device_offload(). The software fallback (fill_sg_in() returns -EINVAL) and the mlx5, nfp and funeth drivers cannot handle such an skb and drop it. Every retransmit rebuilds the same skb, so the connection stalls. Fix this in two places, for defense in depth: 1. Fall back to tcp_rtx_queue_tail(sk) in tcp_write_collapse_fence() when tcp_write_queue_tail(sk) is NULL. 2. Check !skb_cmp_decrypted(to, from) in tcp_skb_can_collapse(), as tcp_skb_can_collapse_rx() does on receive. skb_shift(), which both collapse paths call, already has a DEBUG_NET_WARN_ON_ONCE() for this condition.

Why it matters now

EPSS 0.00559 46th percentileScored 2026-11-07
Fix Partial Linux (Linux): 5.10.273, 5.15.224, 6.1.191 +5Red Hat: 6 without a fix

SSVC decision points

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

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux4.18 and later5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.112, 6.18.55, 7.2.9, 7.3Patch availableCNA
  • Linux VendorLinux Affected 4.18 and later Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.112, 6.18.55, 7.2.9, 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

Upgrade to Linux kernel 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.112, 6.18.55, 7.2.9 or 7.3. Red Hat lists Red Hat Enterprise Linux 8, 9 and 10, Red Hat Enterprise Linux AI (RHEL AI) 3, and Red Hat OpenShift Container Platform 4 and 5 as affected without a fix, with no fix plan available.

Written with Claude Haiku 5.5 from the sources below · 2026-11-05

  • Fix · CNA Linux (Linux) Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.112, 6.18.55, 7.2.9, 7.3

Vendor assessments

Red Hat

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

ProductStatusPlan or fix
Red Hat Enterprise Linux 10AffectedNo fix yet
Red Hat Enterprise Linux 8AffectedNo fix yet
Red Hat Enterprise Linux 9AffectedNo fix yet
Red Hat Enterprise Linux AI (RHEL AI) 3AffectedNo fix yet
Red Hat OpenShift Container Platform 4AffectedNo fix yet
Red Hat OpenShift Container Platform 5AffectedNo fix yet
Not affected: 2 products
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7

Timeline

  1. 2026-10-18 Threatist record created from CVE-2026-98549
  2. 2026-10-18 Alias added: GHSA-p59j-fj4g-255h
  3. 2026-10-19 Fix available: Linux/[email protected] · CNA
  4. 2026-10-20 Affected versions changed · Red Hat
  5. 2026-10-20 CVSS score added · Red Hat
  6. 2026-10-21 Fix available: Linux/[email protected], Linux/Linux@9e2a2f98e8c0197108c6d97a1fa43bfd89071c30 · CNA
  7. 2026-10-21 1 new reference · CNA
  8. 2026-10-24 CVSS score added · CNA
  9. 2026-10-30 Affected versions changed · Red Hat
  10. 2026-10-30 Fix available: Linux/[email protected], Linux/[email protected], Linux/Linux@533344a00ad968181e60d0980c076a9d0de57482 +3 · CNA
  11. 2026-10-30 3 new references · CNA
  12. 2026-11-01 Priority changed: LOW → MEDIUM
  13. 2026-11-05 Affected versions changed · Red Hat
  14. 2026-11-05 CVSS score changed · Red Hat
  15. 2026-11-05 Affected versions changed · Red Hat

References

Other 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-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