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Ubuntu LinuxOperating system · Canonical

CVE-2016-2857

HIGH · 8.4 CVSS v3.1 Published 2016-04-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
86/100
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
The net_checksum_calculate function in net/checksum.c in QEMU allows local guest OS users to cause a denial of service (out-of-bounds heap read and crash) via the payload length in a crafted packet.

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

QEMU's net_checksum_calculate function in net/checksum.c contains an out-of-bounds heap read vulnerability. Local guest OS users can trigger this by sending crafted packets with manipulated payload lengths, causing the function to read beyond allocated buffer boundaries and crash the QEMU process.

MitigationApply available QEMU security updates addressing this vulnerability. Additionally, limit or filter network traffic from untrusted guest VMs to reduce 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
Ubuntu LinuxOperating system
Affected:= 12.04= 14.04= 15.10= 16.04
Debian LinuxOperating system
Affected:= 8.0
OpenstackApplication
Affected:= 5.0= 6.0= 7.0= 8= 9
VirtualizationApplication
Affected:= 3.0= 4.0
Enterprise Linux DesktopOperating system
Affected:= 6.0= 7.0
Enterprise Linux EusOperating system
Affected:= 7.3= 7.4= 7.5= 7.6= 7.7
Enterprise Linux ServerOperating system
Affected:= 6.0= 7.0
Enterprise Linux Server AusOperating system
Affected:= 7.3= 7.4= 7.6= 7.7

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
Changed
Confidentiality
High
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/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. Identify QEMU installation and version
    Run 'qemu-system-x86_64 --version' or 'qemu-img --version' or check package manager: 'dpkg -l | grep qemu' (Debian/Ubuntu) or 'rpm -qa | grep qemu' (Red Hat)
    Affected if Installed QEMU version matches any of the affected versions listed: Ubuntu 12.04, 14.04, 15.10, 16.04; Debian 8.0; Red Hat OpenStack 5.0-9, Virtualization 3.0-4.0, RHEL Desktop 6.0-7.0, RHEL EUS 7.3-7.7, RHEL Server 6.0-7.0, RHEL Server Aus 7.3-7.7
  2. Verify the net/checksum.c code path is reachable
    Check QEMU build for the checksum.ko or net-csum.ko module presence: 'ls /usr/lib/qemu/plugins/' or 'find /usr -name *checksum*'
    Affected if The checksum offload module is loaded or available in the QEMU installation

You are affected if you run any QEMU version matching the listed affected versions AND have network device emulation enabled for guest virtual machines.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply available QEMU security updates addressing this vulnerability. Additionally, limit or filter network traffic from untrusted guest VMs to reduce attack surface.

Fix this in Ubuntu Linux Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing12.0 h
  • Review / QA6.0 h
30.0 hours of engineering $5,120
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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-2016-2857 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