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Linux KernelOperating system · Linux

CVE-2020-35519

HIGH · 7.8 CVSS v3.1 Published 2021-05-06
Fix available
A fix is available. Upgrade to 4.4.248 / 4.9.248 or later.
See remediation →
80/100
Remediation priority · High
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
An out-of-bounds (OOB) memory access flaw was found in x25_bind in net/x25/af_x25.c in the Linux kernel version v5.12-rc5. A bounds check failure allows a local attacker with a user account on the system to gain access to out-of-bounds memory, leading to a system crash or a leak of internal kernel information. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

An out-of-bounds memory access vulnerability exists in the x25_bind function within net/x25/af_x25.c in the Linux kernel. The flaw stems from a bounds check failure that allows a local attacker with a standard user account to access memory outside allocated buffers, potentially causing system crashes or leaking sensitive kernel internal information.

MitigationApply the corresponding Linux kernel security patch to address the bounds check failure in x25_bind. If X.25 protocol support is not required in the environment, it can be disabled via kernel configuration to reduce the attack surface.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 2.6.12, < 4.4.248>= 4.5, < 4.9.248>= 4.10, < 4.14.211>= 4.15, < 4.19.162>= 4.20, < 5.4.82>= 5.5, < 5.9.13
Cloud BackupApplication
Affected:all versions
Solidfire Baseboard Management Controller FirmwareOperating system
Affected:all versions
H300s FirmwareOperating system
Affected:all versions
H500s FirmwareOperating system
Affected:all versions
H700s FirmwareOperating system
Affected:all versions
H300e FirmwareOperating system
Affected:all versions
H500e FirmwareOperating system
Affected:all versions

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check kernel version against affected ranges
    Run 'uname -r' to get the kernel version and compare it to: < 4.4.248, >= 4.5 and < 4.9.248, >= 4.10 and < 4.14.211, >= 4.15 and < 4.19.162, >= 4.20 and < 5.4.82, >= 5.5 and < 5.9.13
    Affected if The installed kernel version falls within any of the listed vulnerable ranges and X.25 protocol support is enabled
  2. Verify X.25 protocol support is enabled
    Check if the X.25 kernel module is loaded with 'lsmod | grep x25' or check kernel config with 'zcat /proc/config.gz 2>/dev/null | grep CONFIG_X25' or 'cat /boot/config-$(uname -r) | grep CONFIG_X25'
    Affected if X.25 module is loaded or CONFIG_X25=y in kernel configuration, and kernel version is vulnerable
  3. Check for active X.25 interfaces or sockets
    Run 'cat /proc/net/x25' or 'ip x25 addr show' to see if any X.25 interfaces are configured
    Affected if Any X.25 interfaces exist and the kernel version is vulnerable
  4. Check NetApp product kernel version
    For NetApp Cloud Backup, Solidfire, or H-series firmware, determine the underlying Linux kernel version through product documentation or system logs
    Affected if The bundled kernel version falls within the affected ranges

You are affected if your kernel version is in any of the listed vulnerable ranges AND X.25 protocol support (CONFIG_X25 or x25 kernel module) is enabled on the system.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Upgrade available Upgrade to 4.4.248 / 4.9.248 / 4.14.211 or later
Fixed in 4.4.2484.9.2484.14.211
Interim mitigation

Apply the corresponding Linux kernel security patch to address the bounds check failure in x25_bind. If X.25 protocol support is not required in the environment, it can be disabled via kernel configuration to reduce the attack surface.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing6.0 h
  • Review / QA3.0 h
14.0 hours of engineering $2,400
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2020-35519 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data