CVE-2021-47129

MEDIUMNVD 4.64.6—
EchelonGraph scoreMEDIUM confidence

Score 4.6 from GitHub Security Advisory published 2024-03-15. NVD baseline CVSS 4.6; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
4.6EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 4.6Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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

netfilter: nft_ct: skip expectations for confirmed conntrack

nft_ct_expect_obj_eval() calls nf_ct_ext_add() for a confirmed conntrack entry. However, nf_ct_ext_add() can only be called for !nf_ct_is_confirmed().

[ 1825.349056] WARNING: CPU: 0 PID: 1279 at net/netfilter/nf_conntrack_extend.c:48 nf_ct_xt_add+0x18e/0x1a0 [nf_conntrack] [ 1825.351391] RIP: 0010:nf_ct_ext_add+0x18e/0x1a0 [nf_conntrack] [ 1825.351493] Code: 41 5c 41 5d 41 5e 41 5f c3 41 bc 0a 00 00 00 e9 15 ff ff ff ba 09 00 00 00 31 f6 4c 89 ff e8 69 6c 3d e9 eb 96 45 31 ed eb cd <0f> 0b e9 b1 fe ff ff e8 86 79 14 e9 eb bf 0f 1f 40 00 0f 1f 44 00 [ 1825.351721] RSP: 0018:ffffc90002e1f1e8 EFLAGS: 00010202 [ 1825.351790] RAX: 000000000000000e RBX: ffff88814f5783c0 RCX: ffffffffc0e4f887 [ 1825.351881] RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff88814f578440 [ 1825.351971] RBP: 0000000000000000 R08: 0000000000000000 R09: ffff88814f578447 [ 1825.352060] R10: ffffed1029eaf088 R11: 0000000000000001 R12: ffff88814f578440 [ 1825.352150] R13: ffff8882053f3a00 R14: 0000000000000000 R15: 0000000000000a20 [ 1825.352240] FS: 00007f992261c900(0000) GS:ffff889faec00000(0000) knlGS:0000000000000000 [ 1825.352343] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1825.352417] CR2: 000056070a4d1158 CR3: 000000015efe0000 CR4: 0000000000350ee0 [ 1825.352508] Call Trace: [ 1825.352544] nf_ct_helper_ext_add+0x10/0x60 [nf_conntrack] [ 1825.352641] nft_ct_expect_obj_eval+0x1b8/0x1e0 [nft_ct] [ 1825.352716] nft_do_chain+0x232/0x850 [nf_tables]

Add the ct helper extension only for unconfirmed conntrack. Skip rule evaluation if the ct helper extension does not exist. Thus, you can only create expectations from the first packet.

It should be possible to remove this limitation by adding a new action to attach a generic ct helper to the first packet. Then, use this ct helper extension from follow up packets to create the ct expectation.

While at it, add a missing check to skip the template conntrack too and remove check for IPCT_UNTRACK which is implicit to !ct.

CVSS v3
4.6
EG Score
4.6MEDIUMmedium confidence
EG Risk
21
EG Risk 21/100CISA SSVC

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
Severity46% × 45%
Exploitation0% × 40%
Automatability0% × 15%
CISA SSVC: Track at every mission impact level.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.4%
EPSS %ILE
36th
KEV
Not listed

CISA SSVCTrack at every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

March 15, 2024

Last Modified

August 5, 2026

References (4)

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 5.10.46-1: fixed in 5.10.46-1
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 5.10.46-1: fixed in 5.10.46-1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 5.10.46-1: fixed in 5.10.46-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 5.10.46-1: fixed in 5.10.46-1
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 8× in last 7d / 31× 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 186 total refreshes for this CVE.

  1. 2026-10-09 20:04 UTCEPSS rescore
  2. 2026-10-08 16:40 UTCEPSS rescore
  3. 2026-10-07 23:45 UTCEPSS rescore
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  10. 2026-09-30 15:45 UTCEG score recompute
  11. 2026-09-30 15:00 UTCEPSS rescore
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  14. 2026-09-26 20:03 UTCOSV refresh
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  1. 2026-09-16 14:05 UTCEPSS rescore
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  8. 2026-09-07 15:58 UTCEPSS rescore
  9. 2026-09-07 05:47 UTCOSV refresh
  10. 2026-09-06 13:45 UTCEPSS rescore
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  24. 2026-08-20 22:52 UTCEPSS rescore
  25. 2026-08-20 15:31 UTCOSV refresh
  26. 2026-08-19 17:01 UTCEPSS rescore
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  40. 2026-08-05 09:43 UTCEG score recompute
  41. 2026-08-05 09:43 UTCGHSA enrichment
  42. 2026-08-04 15:06 UTCEPSS rescore
  43. 2026-08-04 12:20 UTCEG score recompute
  44. 2026-08-04 12:20 UTCGHSA enrichment
  45. 2026-08-04 10:34 UTCEPSS rescore
  46. 2026-08-04 09:53 UTCEG score recompute
  47. 2026-08-04 09:53 UTCGHSA enrichment
  48. 2026-08-03 10:33 UTCEPSS rescore
  49. 2026-08-02 02:24 UTCEPSS rescore
  50. 2026-08-01 10:06 UTCOSV refresh
  51. 2026-08-01 04:13 UTCEPSS rescore
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  60. 2026-07-23 02:06 UTCEG score recompute
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  62. 2026-07-22 14:06 UTCEPSS rescore
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  65. 2026-07-20 17:05 UTCEPSS rescore
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  73. 2026-07-15 01:58 UTCEPSS rescore
  74. 2026-07-15 01:58 UTCEPSS rescore
  75. 2026-07-14 16:55 UTCOSV refresh

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-47129?
CVE-2021-47129 is a medium vulnerability published on March 15, 2024. In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_ct: skip expectations for confirmed conntrack nftctexpectobjeval() calls nfctext_add() for a confirmed conntrack entry. However, nfctext_add() can only be called for !nfctis_confirmed(). [ 1825.349056] WARNING: CPU:…
When was CVE-2021-47129 disclosed?
CVE-2021-47129 was first published on March 15, 2024, with the most recent update on August 5, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-47129 actively exploited?
CVE-2021-47129 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (36th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2021-47129?
CVE-2021-47129 has a CVSS v3 base score of 4.6 (NVD).
How do I remediate CVE-2021-47129?
A fix for CVE-2021-47129 is available: update to the fixed version the vendor names in its advisory.

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