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CVE Record

CVE-2026-31419: net: bonding: fix use-after-free in bond_xmit_broadcast()

In the Linux kernel, the following vulnerability has been resolved: net: bonding: fix use-after-free in bond_xmit_broadcast() bond_xmit_broadcast() reuses the original skb for the last slave (determined by bond_is_last_slave()) and clones it for others. Concurrent slave enslave/release can mutate the slave list during RCU-protected iteration, changing which slave is "last" mid-loop. This causes the original skb to be double-consumed (double-freed). Replace the racy bond_is_last_slave() check with a simple index comparison (i + 1 == slaves_count) against the pre-snapshot slave count taken via READ_ONCE() before the loop. This preserves the zero-copy optimization for the last slave while making the "last" determination stable against concurrent list mutations. The UAF can trigger the following crash: ================================================================== BUG: KASAN: slab-use-after-free in skb_clone Read of size 8 at addr ffff888100ef8d40 by task exploit/147 CPU: 1 UID: 0 PID: 147 Comm: exploit Not tainted 7.0.0-rc3+ #4 PREEMPTLAZY Call Trace: <TASK> dump_stack_lvl (lib/dump_stack.c:123) print_report (mm/kasan/report.c:379 mm/kasan/report.c:482) kasan_report (mm/kasan/report.c:597) skb_clone (include/linux/skbuff.h:1724 include/linux/skbuff.h:1792 include/linux/skbuff.h:3396 net/core/skbuff.c:2108) bond_xmit_broadcast (drivers/net/bonding/bond_main.c:5334) bond_start_xmit (drivers/net/bonding/bond_main.c:5567 drivers/net/bonding/bond_main.c:5593) dev_hard_start_xmit (include/linux/netdevice.h:5325 include/linux/netdevice.h:5334 net/core/dev.c:3871 net/core/dev.c:3887) __dev_queue_xmit (include/linux/netdevice.h:3601 net/core/dev.c:4838) ip6_finish_output2 (include/net/neighbour.h:540 include/net/neighbour.h:554 net/ipv6/ip6_output.c:136) ip6_finish_output (net/ipv6/ip6_output.c:208 net/ipv6/ip6_output.c:219) ip6_output (net/ipv6/ip6_output.c:250) ip6_send_skb (net/ipv6/ip6_output.c:1985) udp_v6_send_skb (net/ipv6/udp.c:1442) udpv6_sendmsg (net/ipv6/udp.c:1733) __sys_sendto (net/socket.c:730 net/socket.c:742 net/socket.c:2206) __x64_sys_sendto (net/socket.c:2209) do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) </TASK> Allocated by task 147: Freed by task 147: The buggy address belongs to the object at ffff888100ef8c80 which belongs to the cache skbuff_head_cache of size 224 The buggy address is located 192 bytes inside of freed 224-byte region [ffff888100ef8c80, ffff888100ef8d60) Memory state around the buggy address: ffff888100ef8c00: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc ffff888100ef8c80: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888100ef8d00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff888100ef8d80: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ffff888100ef8e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A race condition in Linux network bonding can cause kernel memory to be used after it is freed. Under the required local and bonding conditions, this could crash a host and may threaten data confidentiality or integrity. The kernel fix stabilizes how the final bonded interface is selected while transmitting broadcast traffic.

Executive priority

Treat this as a high-priority kernel update for exposed bonded systems, especially shared or critical infrastructure. It is not supported as an Internet-wide emergency: exploitation is local, configuration-dependent, and not reported active in the supplied evidence.

Technical view

During bond_xmit_broadcast(), concurrent slave addition or removal can change which interface appears last during RCU iteration. The original socket buffer may then be consumed twice, causing a double-free and subsequent use-after-free in skb_clone(). The fix selects the last slave using an index and a pre-snapshot slave count.

Likely exposure

Exposure is limited to kernels the supplied record marks affected where bonding broadcast transmission and concurrent slave-list changes can occur. Local access is required under the CVSS vector. Distribution backports make version-string comparisons unreliable, so organizations should confirm status through their Linux vendor.

Exploitation context

The supplied CVSS vector is local, low-complexity, low-privilege, and requires no user interaction. The record includes a reproducible KASAN crash trace, but KEV is false and the supplied sources provide no evidence of active exploitation. A task named "exploit" in the trace is test context, not proof of in-the-wild activity.

Researcher notes

This is CWE-416 with CVSS 3.1 score 7.8: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. The race concerns mutable slave-list ordering versus original-buffer reuse. Exact affected downstream builds cannot be determined from upstream version labels alone; verify vendor backports and advisories.

Mitigation direction

  • Apply vendor kernel packages containing the confirmed bonding fix.
  • Reboot updated systems to ensure the corrected kernel is running.
  • Consult distribution advisories for affected and fixed package versions.
  • Prioritize bonded, multi-user, and network-infrastructure hosts.

Validation and detection

  • Inventory running kernels and compare them with applicable vendor advisories.
  • Identify systems using Linux bonding in broadcast mode.
  • Confirm the running kernel contains the stable fix or a vendor backport.
  • Review kernel logs for use-after-free reports referencing skb_clone or bond_xmit_broadcast.
  • After updating, verify bonded networking remains operational.
Prepared
Confidence
medium
Sources
11

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-416: Exact CWE lookup

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cve · low confidence lookup

CVE-2026-31419 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
1ADP providers
28Source links

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux
7CVSS 3.1HighCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H15.9redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2026-31419Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Reported to Red Hat.

  3. ADP timelineredhat-SADP

    Made public.

  4. CVE publishedCVE Program

    The CVE record was published.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

redhat-SADPkernel: Linux kernel: Use-after-free in bonding driver leads to denial of service
other:Red Hat severity ratingcvssV3_1
  • 2026-04-13T00:00:00.000Z: Reported to Red Hat.
  • 2026-04-13T00:00:00.000Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux4e5bd03ae34652cd932ab4c91c71c511793df75c, 4e5bd03ae34652cd932ab4c91c71c511793df75c, 4e5bd03ae34652cd932ab4c91c71c511793df75c, 4e5bd03ae34652cd932ab4c91c71c511793df75c, 4e5bd03ae34652cd932ab4c91c71c511793df75c, 4e5bd03ae34652cd932ab4c91c71c511793df75c, 20949c3816463e97c6f8fe84c0280c7e5ae83a8d, f1d206181f19b00b275b258fea1418718a2f4173, c1f1691ef84fa6d38fa5e5148eca073145e97ffa, 5.10.94, 5.15.17, 5.16.3unaffected
LinuxLinux5.17, 0, 6.1.184, 6.6.143, 6.12.95, 6.18.22, 6.19.12, 7.0affected
Weakness

CWE details

CWE-416

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.