CVE-2019-20422

Local crash via skipped IPv6 route reference

Published Jan 27, 2020 · Updated Aug 5, 2024

Reference-counting error in the Linux kernel before 5.3.4 allows local users to crash the system through IPv6 route lookup failures. In fib6_rule_lookup, a bitwise OR test makes the no-reference predicate always false and skips dst_hold when the caller expects a retained destination reference. A low-privileged local user can trigger an IPv6 route lookup failure, causing an availability-only kernel crash without data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reference-counting error in the Linux kernel before 5.3.4 allows local users to crash the system through IPv6 route lookup failures. In fib6_rule_lookup, a bitwise OR test makes the no-reference predicate always false and skips dst_hold when the caller expects a retained destination reference. A low-privileged local user can trigger an IPv6 route lookup failure, causing an availability-only kernel crash without data disclosure or modification.

The record

CVE
CVE-2019-20422
Published
Jan 27, 2020
Updated
Aug 5, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-755, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 27, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
2.1NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:P

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-755Improper Handling of Exceptional Conditions
T1499.004Application or System Exploitation

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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