CVE-2020-35519

Kernel disclosure and crash via unterminated X.25 address

Published May 6, 2021 · Updated Aug 4, 2024

Out-of-bounds access in the Linux kernel X.25 implementation in 5.12-rc5 allows local users to disclose kernel memory or crash the system. The x25_bind path passes a user-supplied address that need not be NUL-terminated to strcmp and strlen, allowing reads beyond the sockaddr_x25 buffer. Exploitation requires local code execution and an X.25-enabled kernel; the documented outcomes are a kernel-memory leak and system crash.

CVSS severity7.8
High
EPSS probability0.41%
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 access in the Linux kernel X.25 implementation in 5.12-rc5 allows local users to disclose kernel memory or crash the system. The x25_bind path passes a user-supplied address that need not be NUL-terminated to strcmp and strlen, allowing reads beyond the sockaddr_x25 buffer. Exploitation requires local code execution and an X.25-enabled kernel; the documented outcomes are a kernel-memory leak and system crash.

The record

CVE
CVE-2020-35519
Published
May 6, 2021
Updated
Aug 4, 2024
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-125, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 6, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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?

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

  1. Affected versionversion=v5.12-rc5

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=v5.12-rc5

Published CVSS scores

7.8Canonical UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.8NIST NVDAV:L/AC:L/Au:N/C:C/I:P/A:C
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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
T1068Exploitation for Privilege Escalation

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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