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CVE-2021-47036— udp: skip L4 aggregation for UDP tunnel packets

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel 存在安全漏洞，该漏洞源于如果启用 NETIF_F_GRO_FRAGLIST 或 NETIF_F_GRO_UDP_FWD，并且系统中有可用的 UDP 隧道，则 udp_gro_receive() 最终可能会在外部 UDP 隧道级别为有效携带 UDP 隧道标头的数据包进行 L4 聚合。

CVSS 9.8 · Critical EPSS 0.53% · P43

Possible ATT&CK Techniques 1 AI

T1040.003

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux 9fd1ff5d2ac7181844735806b0a703c942365291< 450687386cd16d081b58cd7a342acff370a96078 affected
9fd1ff5d2ac7181844735806b0a703c942365291< 18f25dc399901426dff61e676ba603ff52c666f7 affected
5.6 affected
< 5.6 unaffected
5.12.4≤ 5.12.* unaffected
5.13≤ * unaffected
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I. Basic Information for CVE-2021-47036

Vulnerability Information
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Vulnerability Title
udp: skip L4 aggregation for UDP tunnel packets
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: udp: skip L4 aggregation for UDP tunnel packets If NETIF_F_GRO_FRAGLIST or NETIF_F_GRO_UDP_FWD are enabled, and there are UDP tunnels available in the system, udp_gro_receive() could end-up doing L4 aggregation (either SKB_GSO_UDP_L4 or SKB_GSO_FRAGLIST) at the outer UDP tunnel level for packets effectively carrying and UDP tunnel header. That could cause inner protocol corruption. If e.g. the relevant packets carry a vxlan header, different vxlan ids will be ignored/ aggregated to the same GSO packet. Inner headers will be ignored, too, so that e.g. TCP over vxlan push packets will be held in the GRO engine till the next flush, etc. Just skip the SKB_GSO_UDP_L4 and SKB_GSO_FRAGLIST code path if the current packet could land in a UDP tunnel, and let udp_gro_receive() do GRO via udp_sk(sk)->gro_receive. The check implemented in this patch is broader than what is strictly needed, as the existing UDP tunnel could be e.g. configured on top of a different device: we could end-up skipping GRO at-all for some packets. Anyhow, that is a very thin corner case and covering it will add quite a bit of complexity. v1 -> v2: - hopefully clarify the commit message
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel 存在安全漏洞，该漏洞源于如果启用 NETIF_F_GRO_FRAGLIST 或 NETIF_F_GRO_UDP_FWD，并且系统中有可用的 UDP 隧道，则 udp_gro_receive() 最终可能会在外部 UDP 隧道级别为有效携带 UDP 隧道标头的数据包进行 L4 聚合。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 9fd1ff5d2ac7181844735806b0a703c942365291 ~ 450687386cd16d081b58cd7a342acff370a96078 -
Linux Linux 5.6 -

II. Public POCs for CVE-2021-47036

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III. Intelligence Information for CVE-2021-47036

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Other References for CVE-2021-47036 (2)

Same Patch Batch · Linux · 2024-02-28 · 86 CVEs total

CVE-2021-47013 9.8 CRITICAL net:emac/emac-mac: Fix a use after free in emac_mac_tx_buf_send
CVE-2021-46999 9.8 CRITICAL sctp: do asoc update earlier in sctp_sf_do_dupcook_a
CVE-2021-47017 8.8 HIGH ath10k: Fix a use after free in ath10k_htc_send_bundle
CVE-2021-47035 8.8 HIGH iommu/vt-d: Remove WO permissions on second-level paging entries
CVE-2021-47049 8.4 HIGH Drivers: hv: vmbus: Use after free in __vmbus_open()
CVE-2021-47040 7.8 HIGH io_uring: fix overflows checks in provide buffers
CVE-2021-47048 7.8 HIGH spi: spi-zynqmp-gqspi: fix use-after-free in zynqmp_qspi_exec_op
CVE-2021-46998 7.8 HIGH ethernet:enic: Fix a use after free bug in enic_hard_start_xmit
CVE-2020-36787 7.8 HIGH media: aspeed: fix clock handling logic
CVE-2021-46993 7.8 HIGH sched: Fix out-of-bound access in uclamp
CVE-2021-46984 7.8 HIGH kyber: fix out of bounds access when preempted
CVE-2020-36785 7.8 HIGH media: atomisp: Fix use after free in atomisp_alloc_css_stat_bufs()
CVE-2021-46992 7.8 HIGH netfilter: nftables: avoid overflows in nft_hash_buckets()
CVE-2021-47014 7.8 HIGH net/sched: act_ct: fix wild memory access when clearing fragments
CVE-2021-46977 7.8 HIGH KVM: VMX: Disable preemption when probing user return MSRs
CVE-2021-47012 7.8 HIGH RDMA/siw: Fix a use after free in siw_alloc_mr
CVE-2021-47011 7.8 HIGH mm: memcontrol: slab: fix obtain a reference to a freeing memcg
CVE-2021-46983 7.5 HIGH nvmet-rdma: Fix NULL deref when SEND is completed with error
CVE-2021-47001 7.5 HIGH xprtrdma: Fix cwnd update ordering
CVE-2021-47041 7.5 HIGH nvmet-tcp: fix incorrect locking in state_change sk callback

Showing top 20 of 86 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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