CVE-2021-47309

Kernel memory disclosure or crash via metadata miscast

Published May 21, 2024 · Updated Aug 5, 2026

Out-of-bounds read in Linux tunnel metadata handling allows local users to disclose kernel memory or crash the system. skb_tunnel_info() treats lwtstate->data as ip_tunnel_info without validating the metadata type, so VXLAN reads beyond an incompatible MPLS encapsulation object. Triggering the flaw requires local low-privileged access and a routing path that passes MPLS lightweight-tunnel metadata into VXLAN transmission.

CVSS severity7.1
High
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in Linux tunnel metadata handling allows local users to disclose kernel memory or crash the system. skb_tunnel_info() treats lwtstate->data as ip_tunnel_info without validating the metadata type, so VXLAN reads beyond an incompatible MPLS encapsulation object. Triggering the flaw requires local low-privileged access and a routing path that passes MPLS lightweight-tunnel metadata into VXLAN transmission.

The record

CVE
CVE-2021-47309
Published
May 21, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-125, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.3
  2. Affected versionversion=61adedf3e3f1d3f032c5a6a299978d91eff6d555 <2179d96ec702cc33ead02a9ce40ece599b8538c5
  3. Affected versionversion=61adedf3e3f1d3f032c5a6a299978d91eff6d555 <67a9c94317402b826fc3db32afc8f39336803d97
  4. Affected versionversion=61adedf3e3f1d3f032c5a6a299978d91eff6d555 <83bdcfbd968bcc91a0632b7b625e4a9b0cba5e0d
  5. Affected versionversion=61adedf3e3f1d3f032c5a6a299978d91eff6d555 <8aa13a86964cdec4fd969ef677c6614ff068641a
  6. Affected versionversion=61adedf3e3f1d3f032c5a6a299978d91eff6d555 <8bb1589c89e61e3b182dd546f1021928ebb5c2a6
  7. Affected versionversion=61adedf3e3f1d3f032c5a6a299978d91eff6d555 <a915379594f1e045421635c6316d8f3ffa018c58
  8. Affected versionversion=61adedf3e3f1d3f032c5a6a299978d91eff6d555 <b61d327cd3cc5ea591f3bf751dd11e034f388bb5
  9. Affected versionversion=61adedf3e3f1d3f032c5a6a299978d91eff6d555 <e7f3c9df40515a6c6b46f36c4c94cf48a043f887

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.3; version=61adedf3e3f1d3f032c5a6a299978d91eff6d555 <2179d96ec702cc33ead02a9ce40ece599b8538c5; version=61adedf3e3f1d3f032c5a6a299978d91eff6d555 <67a9c94317402b826fc3db32afc8f39336803d97; version=61adedf3e3f1d3f032c5a6a299978d91eff6d555 <83bdcfbd968bcc91a0632b7b625e4a9b0cba5e0d; version=61adedf3e3f1d3f032c5a6a299978d91eff6d555 <8aa13a86964cdec4fd969ef677c6614ff068641a; version=61adedf3e3f1d3f032c5a6a299978d91eff6d555 <8bb1589c89e61e3b182dd546f1021928ebb5c2a6; version=61adedf3e3f1d3f032c5a6a299978d91eff6d555 <a915379594f1e045421635c6316d8f3ffa018c58; version=61adedf3e3f1d3f032c5a6a299978d91eff6d555 <b61d327cd3cc5ea591f3bf751dd11e034f388bb5; version=61adedf3e3f1d3f032c5a6a299978d91eff6d555 <e7f3c9df40515a6c6b46f36c4c94cf48a043f887

Published CVSS scores

7.1CanonicalCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
7.1NISTCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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