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Linux Kernel RtOperating system · Linux

CVE-2016-3707

HIGH · 8.1 CVSS v3.0 Published 2016-06-27
Fix available
A fix is available. Upgrade to after 3.10.0 or later.
See remediation →
90/100
Remediation priority · Urgent
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
The icmp_check_sysrq function in net/ipv4/icmp.c in the kernel.org projects/rt patches for the Linux kernel, as used in the kernel-rt package before 3.10.0-327.22.1 in Red Hat Enterprise Linux for Real Time 7 and other products, allows remote attackers to execute SysRq commands via crafted ICMP Echo Request packets, as demonstrated by a brute-force attack to discover a cookie, or an attack that occurs after reading the local icmp_echo_sysrq file.

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 · moderate confidence

A vulnerability in the icmp_check_sysrq function in net/ipv4/icmp.c allows remote attackers to execute arbitrary SysRq commands via crafted ICMP Echo Request packets. The attack can be performed via brute-force to discover a cookie, or by reading the local icmp_echo_sysrq file to obtain the necessary value.

MitigationUpdate the kernel-rt package to version 3.10.0-327.22.1 or later. Alternatively, disable ICMP Echo Request processing or restrict network access to prevent unauthenticated ICMP traffic.

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 Kernel RtOperating system
Affected:<= 3.10.0
Enterprise Linux For Real TimeOperating system
Affected:= 7
Enterprise Linux For Real Time For NfvOperating system
Affected:= 7
Suse Linux Enterprise Real Time ExtensionOperating system
Affected:= 12.0

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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:H/PR:N/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. Confirm if a Real-Time kernel is in use
    Run 'uname -r' and check if the output contains 'rt' (e.g., '3.10.0-327.rt56.234.el7.x86_64')
    Affected if The kernel version string contains 'rt' indicating a Real-Time kernel variant, as this vulnerability only affects RT kernels
  2. Check the kernel version number
    Run 'uname -r' and compare the version to the affected range. For RT kernels, check if the version is <= 3.10.0-327.21.1 (the last vulnerable version)
    Affected if The installed RT kernel version is 3.10.0 or lower and was not patched to 3.10.0-327.22.1 or later
  3. Verify ICMP Echo Request processing is enabled
    Check if the system accepts ICMP Echo Requests by attempting to ping the local host ('ping -c 1 127.0.0.1') or checking /proc/sys/net/ipv4/icmp_echo_enable
    Affected if ICMP Echo Requests are allowed, which is required for the attacker to send the crafted packets
  4. Check if SysRq over ICMP is accessible
    Inspect the /proc/sys/net/ipv4/icmp_echo_sysrq file (if it exists) to see if SysRq via ICMP is configured. Run 'cat /proc/sys/net/ipv4/icmp_echo_sysrq 2>/dev/null'
    Affected if This file is readable or writable, allowing attackers to obtain or brute-force the required cookie value

A system is affected if it runs a Real-Time (RT) kernel version at or below 3.10.0 that accepts ICMP Echo Requests and exposes the icmp_echo_sysrq interface, allowing remote attackers to inject SysRq commands.

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 3.10.0
Interim mitigation

Update the kernel-rt package to version 3.10.0-327.22.1 or later. Alternatively, disable ICMP Echo Request processing or restrict network access to prevent unauthenticated ICMP traffic.

Fix this in Linux Kernel Rt Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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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-2016-3707 in production — separate from our analysis above.

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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