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CVE Record

CVE-2025-21960: eth: bnxt: do not update checksum in bnxt_xdp_build_skb()

In the Linux kernel, the following vulnerability has been resolved: eth: bnxt: do not update checksum in bnxt_xdp_build_skb() The bnxt_rx_pkt() updates ip_summed value at the end if checksum offload is enabled. When the XDP-MB program is attached and it returns XDP_PASS, the bnxt_xdp_build_skb() is called to update skb_shared_info. The main purpose of bnxt_xdp_build_skb() is to update skb_shared_info, but it updates ip_summed value too if checksum offload is enabled. This is actually duplicate work. When the bnxt_rx_pkt() updates ip_summed value, it checks if ip_summed is CHECKSUM_NONE or not. It means that ip_summed should be CHECKSUM_NONE at this moment. But ip_summed may already be updated to CHECKSUM_UNNECESSARY in the XDP-MB-PASS path. So the by skb_checksum_none_assert() WARNS about it. This is duplicate work and updating ip_summed in the bnxt_xdp_build_skb() is not needed. Splat looks like: WARNING: CPU: 3 PID: 5782 at ./include/linux/skbuff.h:5155 bnxt_rx_pkt+0x479b/0x7610 [bnxt_en] Modules linked in: bnxt_re bnxt_en rdma_ucm rdma_cm iw_cm ib_cm ib_uverbs veth xt_nat xt_tcpudp xt_conntrack nft_chain_nat xt_MASQUERADE nf_] CPU: 3 UID: 0 PID: 5782 Comm: socat Tainted: G W 6.14.0-rc4+ #27 Tainted: [W]=WARN Hardware name: ASUS System Product Name/PRIME Z690-P D4, BIOS 0603 11/01/2021 RIP: 0010:bnxt_rx_pkt+0x479b/0x7610 [bnxt_en] Code: 54 24 0c 4c 89 f1 4c 89 ff c1 ea 1f ff d3 0f 1f 00 49 89 c6 48 85 c0 0f 84 4c e5 ff ff 48 89 c7 e8 ca 3d a0 c8 e9 8f f4 ff ff <0f> 0b f RSP: 0018:ffff88881ba09928 EFLAGS: 00010202 RAX: 0000000000000000 RBX: 00000000c7590303 RCX: 0000000000000000 RDX: 1ffff1104e7d1610 RSI: 0000000000000001 RDI: ffff8881c91300b8 RBP: ffff88881ba09b28 R08: ffff888273e8b0d0 R09: ffff888273e8b070 R10: ffff888273e8b010 R11: ffff888278b0f000 R12: ffff888273e8b080 R13: ffff8881c9130e00 R14: ffff8881505d3800 R15: ffff888273e8b000 FS: 00007f5a2e7be080(0000) GS:ffff88881ba00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fff2e708ff8 CR3: 000000013e3b0000 CR4: 00000000007506f0 PKRU: 55555554 Call Trace: <IRQ> ? __warn+0xcd/0x2f0 ? bnxt_rx_pkt+0x479b/0x7610 ? report_bug+0x326/0x3c0 ? handle_bug+0x53/0xa0 ? exc_invalid_op+0x14/0x50 ? asm_exc_invalid_op+0x16/0x20 ? bnxt_rx_pkt+0x479b/0x7610 ? bnxt_rx_pkt+0x3e41/0x7610 ? __pfx_bnxt_rx_pkt+0x10/0x10 ? napi_complete_done+0x2cf/0x7d0 __bnxt_poll_work+0x4e8/0x1220 ? __pfx___bnxt_poll_work+0x10/0x10 ? __pfx_mark_lock.part.0+0x10/0x10 bnxt_poll_p5+0x36a/0xfa0 ? __pfx_bnxt_poll_p5+0x10/0x10 __napi_poll.constprop.0+0xa0/0x440 net_rx_action+0x899/0xd00 ... Following ping.py patch adds xdp-mb-pass case. so ping.py is going to be able to reproduce this issue.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Linux Broadcom network-driver flaw can mishandle packet checksum state when an XDP multi-buffer program allows traffic through. This triggers a kernel warning and is rated as a high availability risk. It matters primarily to systems using the bnxt driver with this specialized XDP configuration, not every Linux host.

Executive priority

Treat as high priority for confirmed bnxt_en systems using XDP multi-buffer packet processing, especially availability-sensitive infrastructure. For other Linux systems, first validate the required driver and XDP configuration before escalating emergency work. No active exploitation is established by the supplied sources.

Technical view

In bnxt_en, bnxt_xdp_build_skb() redundantly changes skb ip_summed during the XDP-MB XDP_PASS path. bnxt_rx_pkt() later expects CHECKSUM_NONE before applying checksum-offload state, causing skb_checksum_none_assert() to warn. The cited stable-kernel commits remove the duplicate update. The supplied CVSS is 7.5, reflecting network-reachable availability impact without confidentiality or integrity impact.

Likely exposure

Exposure requires an affected Linux kernel, the Broadcom bnxt_en network driver, checksum offload, and an attached XDP multi-buffer program returning XDP_PASS. Hosts without that combination are unlikely to encounter this specific path. The supplied version data is ambiguous, so distribution package status and vendor advisories should determine exposure.

Exploitation context

The bundle provides a reproducible test-path description but no evidence of malicious exploitation. CVE-2025-21960 is not listed as KEV in the supplied data. Network reachability is represented in the CVSS vector, but the sources do not establish practical remote exploitation conditions, widespread attacks, or a public weaponized exploit.

Researcher notes

The defect is a duplicated skb checksum-state update in the XDP-MB pass path, producing an assertion warning when bnxt_rx_pkt() performs its expected update. The source bundle lists several affected and commit-like version values without clear range semantics. Validate fixes using distribution backport records rather than kernel version comparison alone.

Mitigation direction

  • Apply a supported kernel update containing the applicable cited stable-kernel fix.
  • Use distribution or hardware-vendor advisories to identify the correct fixed package.
  • Prioritize affected hosts performing XDP-based packet processing with bnxt_en interfaces.
  • If updates are unavailable, request vendor-approved temporary mitigation guidance.

Validation and detection

  • Inventory kernel versions and distribution package revisions on systems using bnxt_en.
  • Confirm whether XDP multi-buffer programs are attached to bnxt_en interfaces.
  • Determine whether checksum offload is enabled on those interfaces.
  • Review kernel logs for bnxt_rx_pkt or skb_checksum_none_assert warnings.
  • Verify the installed update incorporates the applicable stable-kernel fix.
Prepared
Confidence
medium
Sources
8

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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CVE-2025-21960 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

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

1CVSS vectors
3Timeline events
1ADP providers
7Source links

CVSS vector scores

1 official score

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
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2025-21960Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

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

ADP provider summaries

CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux1dc4c557bfedfcdf7fc0c46795857773b7ad66e7, 1dc4c557bfedfcdf7fc0c46795857773b7ad66e7, 1dc4c557bfedfcdf7fc0c46795857773b7ad66e7, 1dc4c557bfedfcdf7fc0c46795857773b7ad66e7, 1dc4c557bfedfcdf7fc0c46795857773b7ad66e7unaffected
LinuxLinux5.19, 0, 6.1.132, 6.6.84, 6.12.20, 6.13.8, 6.14affected
Weakness

CWE details

No CWE listed

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