CVE-2021-47099

MEDIUMNVD 6.06.0—
EchelonGraph scoreMEDIUM confidence

Score 6.0 from GitHub Security Advisory published 2024-03-04. NVD baseline CVSS 6.0; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
6.0EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.0Exploit: None knownExposed: 0

A fix is available — apply it.

In the Linux kernel, the following vulnerability has been resolved:

veth: ensure skb entering GRO are not cloned.

After commit d3256efd8e8b ("veth: allow enabling NAPI even without XDP"), if GRO is enabled on a veth device and TSO is disabled on the peer device, TCP skbs will go through the NAPI callback. If there is no XDP program attached, the veth code does not perform any share check, and shared/cloned skbs could enter the GRO engine.

Ignat reported a BUG triggered later-on due to the above condition:

[ 53.970529][ C1] kernel BUG at net/core/skbuff.c:3574! [ 53.981755][ C1] invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI [ 53.982634][ C1] CPU: 1 PID: 19 Comm: ksoftirqd/1 Not tainted 5.16.0-rc5+ #25 [ 53.982634][ C1] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 [ 53.982634][ C1] RIP: 0010:skb_shift+0x13ef/0x23b0 [ 53.982634][ C1] Code: ea 03 0f b6 04 02 48 89 fa 83 e2 07 38 d0 7f 08 84 c0 0f 85 41 0c 00 00 41 80 7f 02 00 4d 8d b5 d0 00 00 00 0f 85 74 f5 ff ff <0f> 0b 4d 8d 77 20 be 04 00 00 00 4c 89 44 24 78 4c 89 f7 4c 89 8c [ 53.982634][ C1] RSP: 0018:ffff8881008f7008 EFLAGS: 00010246 [ 53.982634][ C1] RAX: 0000000000000000 RBX: ffff8881180b4c80 RCX: 0000000000000000 [ 53.982634][ C1] RDX: 0000000000000002 RSI: ffff8881180b4d3c RDI: ffff88810bc9cac2 [ 53.982634][ C1] RBP: ffff8881008f70b8 R08: ffff8881180b4cf4 R09: ffff8881180b4cf0 [ 53.982634][ C1] R10: ffffed1022999e5c R11: 0000000000000002 R12: 0000000000000590 [ 53.982634][ C1] R13: ffff88810f940c80 R14: ffff88810f940d50 R15: ffff88810bc9cac0 [ 53.982634][ C1] FS: 0000000000000000(0000) GS:ffff888235880000(0000) knlGS:0000000000000000 [ 53.982634][ C1] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 53.982634][ C1] CR2: 00007ff5f9b86680 CR3: 0000000108ce8004 CR4: 0000000000170ee0 [ 53.982634][ C1] Call Trace: [ 53.982634][ C1] [ 53.982634][ C1] tcp_sacktag_walk+0xaba/0x18e0 [ 53.982634][ C1] tcp_sacktag_write_queue+0xe7b/0x3460 [ 53.982634][ C1] tcp_ack+0x2666/0x54b0 [ 53.982634][ C1] tcp_rcv_established+0x4d9/0x20f0 [ 53.982634][ C1] tcp_v4_do_rcv+0x551/0x810 [ 53.982634][ C1] tcp_v4_rcv+0x22ed/0x2ed0 [ 53.982634][ C1] ip_protocol_deliver_rcu+0x96/0xaf0 [ 53.982634][ C1] ip_local_deliver_finish+0x1e0/0x2f0 [ 53.982634][ C1] ip_sublist_rcv_finish+0x211/0x440 [ 53.982634][ C1] ip_list_rcv_finish.constprop.0+0x424/0x660 [ 53.982634][ C1] ip_list_rcv+0x2c8/0x410 [ 53.982634][ C1] __netif_receive_skb_list_core+0x65c/0x910 [ 53.982634][ C1] netif_receive_skb_list_internal+0x5f9/0xcb0 [ 53.982634][ C1] napi_complete_done+0x188/0x6e0 [ 53.982634][ C1] gro_cell_poll+0x10c/0x1d0 [ 53.982634][ C1] __napi_poll+0xa1/0x530 [ 53.982634][ C1] net_rx_action+0x567/0x1270 [ 53.982634][ C1] __do_softirq+0x28a/0x9ba [ 53.982634][ C1] run_ksoftirqd+0x32/0x60 [ 53.982634][ C1] smpboot_thread_fn+0x559/0x8c0 [ 53.982634][ C1] kthread+0x3b9/0x490 [ 53.982634][ C1] ret_from_fork+0x22/0x30 [ 53.982634][ C1]

Address the issue by skipping the GRO stage for shared or cloned skbs. To reduce the chance of OoO, try to unclone the skbs before giving up.

v1 -> v2:

  • use avoid skb_copy and fallback to netif_receive_skb - Eric

CVSS v3
6.0
EG Score
6.0(medium)
EG Risk
27(Track)
EG Risk 27/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity60% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
11%
KEV
Not listed

Published

March 4, 2024

Last Modified

April 8, 2025

References (4)

Vendor Advisories for CVE-2021-47099(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(5)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatkernel-0:4.18.0-372.100.1.el8_62024-04-18redhat
redhatkernel-rt-0:5.14.0-162.6.1.rt21.168.el9_12022-11-15redhat
redhatkernel-0:5.14.0-162.6.1.el9_12022-11-15redhat
redhatkernel-rt-0:4.18.0-425.3.1.rt7.213.el82022-11-08redhat
redhatkernel-0:4.18.0-425.3.1.el82022-11-08redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Additional Vendor Advisories

(3)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 11× in last 7d / 46× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 106 total refreshes for this CVE.

  1. 2026-07-26 14:52 UTCEPSS rescore
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Related CVEs(same vendor)

Frequently asked(5)

What is CVE-2021-47099?
CVE-2021-47099 is a medium vulnerability published on March 4, 2024. In the Linux kernel, the following vulnerability has been resolved: veth: ensure skb entering GRO are not cloned. After commit d3256efd8e8b ("veth: allow enabling NAPI even without XDP"), if GRO is enabled on a veth device and TSO is disabled on the peer device, TCP skbs will go through the NAPI…
When was CVE-2021-47099 disclosed?
CVE-2021-47099 was first published in the National Vulnerability Database on March 4, 2024, with the most recent update on April 8, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-47099 actively exploited?
CVE-2021-47099 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 88.8% of all scored CVEs.
What is the CVSS score of CVE-2021-47099?
CVE-2021-47099 has a CVSS v3 base score of 6.0 (NVD).
How do I remediate CVE-2021-47099?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-47099, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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