CVE-2025-21961

CVE-2025-21961 is a medium-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Description

In the Linux kernel, the following vulnerability has been resolved: eth: bnxt: fix truesize for mb-xdp-pass case When mb-xdp is set and return is XDP_PASS, packet is converted from xdp_buff to sk_buff with xdp_update_skb_shared_info() in bnxt_xdp_build_skb(). bnxt_xdp_build_skb() passes incorrect truesize argument to xdp_update_skb_shared_info(). The truesize is calculated as BNXT_RX_PAGE_SIZE * sinfo->nr_frags but the skb_shared_info was wiped by napi_build_skb() before. So it stores sinfo->nr_frags before bnxt_xdp_build_skb() and use it instead of getting skb_shared_info from xdp_get_shared_info_from_buff(). Splat looks like: ------------[ cut here ]------------ WARNING: CPU: 2 PID: 0 at net/core/skbuff.c:6072 skb_try_coalesce+0x504/0x590 Modules linked in: xt_nat xt_tcpudp veth af_packet xt_conntrack nft_chain_nat xt_MASQUERADE nf_conntrack_netlink xfrm_user xt_addrtype nft_coms CPU: 2 UID: 0 PID: 0 Comm: swapper/2 Not tainted 6.14.0-rc2+ #3 RIP: 0010:skb_try_coalesce+0x504/0x590 Code: 4b fd ff ff 49 8b 34 24 40 80 e6 40 0f 84 3d fd ff ff 49 8b 74 24 48 40 f6 c6 01 0f 84 2e fd ff ff 48 8d 4e ff e9 25 fd ff ff <0f> 0b e99 RSP: 0018:ffffb62c4120caa8 EFLAGS: 00010287 RAX: 0000000000000003 RBX: ffffb62c4120cb14 RCX: 0000000000000ec0 RDX: 0000000000001000 RSI: ffffa06e5d7dc000 RDI: 0000000000000003 RBP: ffffa06e5d7ddec0 R08: ffffa06e6120a800 R09: ffffa06e7a119900 R10: 0000000000002310 R11: ffffa06e5d7dcec0 R12: ffffe4360575f740 R13: ffffe43600000000 R14: 0000000000000002 R15: 0000000000000002 FS: 0000000000000000(0000) GS:ffffa0755f700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f147b76b0f8 CR3: 00000001615d4000 CR4: 00000000007506f0 PKRU: 55555554 Call Trace: <IRQ> ? __warn+0x84/0x130 ? skb_try_coalesce+0x504/0x590 ? report_bug+0x18a/0x1a0 ? handle_bug+0x53/0x90 ? exc_invalid_op+0x14/0x70 ? asm_exc_invalid_op+0x16/0x20 ? skb_try_coalesce+0x504/0x590 inet_frag_reasm_finish+0x11f/0x2e0 ip_defrag+0x37a/0x900 ip_local_deliver+0x51/0x120 ip_sublist_rcv_finish+0x64/0x70 ip_sublist_rcv+0x179/0x210 ip_list_rcv+0xf9/0x130 How to reproduce: <Node A> ip link set $interface1 xdp obj xdp_pass.o ip link set $interface1 mtu 9000 up ip a a 10.0.0.1/24 dev $interface1 <Node B> ip link set $interfac2 mtu 9000 up ip a a 10.0.0.2/24 dev $interface2 ping 10.0.0.1 -s 65000 Following ping.py patch adds xdp-mb-pass case. so ping.py is going to be able to reproduce this issue.

Frequently asked questions

What is CVE-2025-21961?
In the Linux kernel, the following vulnerability has been resolved: eth: bnxt: fix truesize for mb-xdp-pass case When mb-xdp is set and return is XDP_PASS, packet is converted from xdp_buff to sk_buff with xdp_update_skb_shared_info() in bnxt_xdp_build_skb(). bnxt_xdp_build_skb() passes incorrect truesize argument to xdp_update_skb_shared_info(). The truesize is calculated as BNXT_RX_PAGE_SIZE * sinfo->nr_frags but the skb_shared_info was wiped by napi_build_skb() before. So it stores sinfo->nr_frags before bnxt_xdp_build_skb() and use it instead of getting skb_shared_info from xdp_get_shared_info_from_buff(). Splat looks like: ------------[ cut here ]------------ WARNING: CPU: 2 PID: 0 at net/core/skbuff.c:6072 skb_try_coalesce+0x504/0x590 Modules linked in: xt_nat xt_tcpudp veth af_packet xt_conntrack nft_chain_nat xt_MASQUERADE nf_conntrack_netlink xfrm_user xt_addrtype nft_coms CPU: 2 UID: 0 PID: 0 Comm: swapper/2 Not tainted 6.14.0-rc2+ #3 RIP: 0010:skb_try_coalesce+0x504/0x590 Code: 4b fd ff ff 49 8b 34 24 40 80 e6 40 0f 84 3d fd ff ff 49 8b 74 24 48 40 f6 c6 01 0f 84 2e fd ff ff 48 8d 4e ff e9 25 fd ff ff <0f> 0b e99 RSP: 0018:ffffb62c4120caa8 EFLAGS: 00010287 RAX: 0000000000000003 RBX: ffffb62c4120cb14 RCX: 0000000000000ec0 RDX: 0000000000001000 RSI: ffffa06e5d7dc000 RDI: 0000000000000003 RBP: ffffa06e5d7ddec0 R08: ffffa06e6120a800 R09: ffffa06e7a119900 R10: 0000000000002310 R11: ffffa06e5d7dcec0 R12: ffffe4360575f740 R13: ffffe43600000000 R14: 0000000000000002 R15: 0000000000000002 FS: 0000000000000000(0000) GS:ffffa0755f700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f147b76b0f8 CR3: 00000001615d4000 CR4: 00000000007506f0 PKRU: 55555554 Call Trace: <IRQ> ? __warn+0x84/0x130 ? skb_try_coalesce+0x504/0x590 ? report_bug+0x18a/0x1a0 ? handle_bug+0x53/0x90 ? exc_invalid_op+0x14/0x70 ? asm_exc_invalid_op+0x16/0x20 ? skb_try_coalesce+0x504/0x590 inet_frag_reasm_finish+0x11f/0x2e0 ip_defrag+0x37a/0x900 ip_local_deliver+0x51/0x120 ip_sublist_rcv_finish+0x64/0x70 ip_sublist_rcv+0x179/0x210 ip_list_rcv+0xf9/0x130 How to reproduce: <Node A> ip link set $interface1 xdp obj xdp_pass.o ip link set $interface1 mtu 9000 up ip a a 10.0.0.1/24 dev $interface1 <Node B> ip link set $interfac2 mtu 9000 up ip a a 10.0.0.2/24 dev $interface2 ping 10.0.0.1 -s 65000 Following ping.py patch adds xdp-mb-pass case. so ping.py is going to be able to reproduce this issue.
How severe is CVE-2025-21961?
CVE-2025-21961 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2025-21961 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (8th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-21961?
CVE-2025-21961 primarily affects Linux Linux Kernel. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2025-21961?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-21961 have an EU (EUVD) identifier?
Yes. CVE-2025-21961 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-9359.
When was CVE-2025-21961 published?
CVE-2025-21961 was published on 2025-04-01 and last updated on 2026-06-17.

References

Affected products (7)

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