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Linux KernelOperating system · Linux

CVE-2009-4537

HIGH · 7.8 CVSS v2.0 Published 2010-01-12
Fix available
A fix is available. Upgrade to after 2.6.32.3 or later.
See remediation →
87/100
Remediation priority · High
Remotely reachable No privileges 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
drivers/net/r8169.c in the r8169 driver in the Linux kernel 2.6.32.3 and earlier does not properly check the size of an Ethernet frame that exceeds the MTU, which allows remote attackers to (1) cause a denial of service (temporary network outage) via a packet with a crafted size, in conjunction with certain packets containing A characters and certain packets containing E characters; or (2) cause a denial of service (system crash) via a packet with a crafted size, in conjunction with certain packets containing '\0' characters, related to the value of the status register and erroneous behavior associated with the RxMaxSize register. NOTE: this vulnerability exists because of an incorrect fix for CVE-2009-1389.

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

The r8169 network driver in Linux kernel 2.6.32.3 and earlier fails to properly validate Ethernet frame sizes that exceed the configured MTU. This improper boundary check allows remote attackers to send specially crafted packets that either cause a temporary network outage (when combined with packets containing 'A' and 'E' characters) or trigger a kernel panic/system crash (when combined with packets containing null bytes), due to erroneous handling of the RxMaxSize register and status register conditions.

MitigationApply the correct vendor-supplied kernel patch that properly validates incoming frame sizes against MTU and RxMaxSize limits, or upgrade to a kernel version where this issue has been correctly resolved (post-CVE-2009-1389 regression fix).

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:<= 2.6.32.3
Debian LinuxOperating system
Affected:= 5.0

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
Network
Complexity
Low
Authentication
None
Confidentiality
None
Integrity
None
Availability
Complete

AV:N/AC:L/Au:N/C:N/I:N/A:C

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
    Run `uname -r` to obtain the running kernel version and compare it to 2.6.32.3 (versions 2.6.32.3 and earlier are affected)
    Affected if The kernel version is 2.6.32.3 or earlier
  2. Identify network interface driver
    Run `ethtool -i eth0` (replace eth0 with the relevant interface) or `lspci -v | grep -A5 Ethernet` to determine which driver handles the network interface
    Affected if The network interface uses the r8169 driver
  3. Verify r8169 driver is loaded
    Run `lsmod | grep r8169` to check if the r8169 kernel module is currently loaded
    Affected if The r8169 module is loaded
  4. Check Debian version (if applicable)
    Run `cat /etc/debian_version` to identify the Debian release; Debian 5.0 (Lenny) is listed as affected
    Affected if The system is running Debian 5.0 with a vulnerable kernel

A system is affected if it runs Linux kernel 2.6.32.3 or earlier with the r8169 network driver loaded and handling a network interface

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 a release after 2.6.32.3
Interim mitigation

Apply the correct vendor-supplied kernel patch that properly validates incoming frame sizes against MTU and RxMaxSize limits, or upgrade to a kernel version where this issue has been correctly resolved (post-CVE-2009-1389 regression fix).

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
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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-2009-4537 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