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GlibcFramework / library · Gnu

CVE-2017-18269

CRITICAL · 9.8 CVSS v3.0 Published 2018-05-18
Fix available
A fix is available. Upgrade to after 2.27 or later.
See remediation →
100/100
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
An SSE2-optimized memmove implementation for i386 in sysdeps/i386/i686/multiarch/memcpy-sse2-unaligned.S in the GNU C Library (aka glibc or libc6) 2.21 through 2.27 does not correctly perform the overlapping memory check if the source memory range spans the middle of the address space, resulting in corrupt data being produced by the copy operation. This may disclose information to context-dependent attackers, or result in a denial of service, or, possibly, code execution.

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 SSE2-optimized memmove implementation for i386 in glibc 2.21-2.27 contains a faulty overlapping memory check that fails when the source memory range spans the middle of the address space, causing data corruption and potentially enabling information disclosure, denial of service, or code execution.

MitigationUpdate glibc to version 2.28 or later where the overlapping memory check bug in the SSE2-optimized memmove was fixed.

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
GlibcFramework / library
Affected:>= 2.21, <= 2.27

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

CVSS:3.0/AV:N/AC:L/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. Identify system architecture
    Run 'uname -m' or 'dpkg --print-architecture' to determine if the system is running a 32-bit x86 (i386/i686) architecture. This vulnerability exists only in the i386-specific SSE2-optimized memmove implementation.
    Affected if The architecture is i386 or i686 (32-bit x86)
  2. Locate the glibc library
    Run 'ldd --version' or check '/lib32/libc.so.6' (on 32-bit systems) or '/lib/i386-linux-gnu/libc.so.6' to identify the installed glibc library file.
    Affected if A glibc library file exists on the system
  3. Determine glibc version
    Run 'ldd --version' to display the glibc version, or use 'strings /lib32/libc.so.6 | grep -E "^[0-9]+\.[0-9]+"' to extract version information from the libc library file.
    Affected if The reported glibc version is between 2.21 and 2.27 inclusive
  4. Verify SSE2 support on i386
    On 32-bit x86 systems, the SSE2-optimized memmove is used when the CPU supports SSE2. Check CPU capabilities via 'cat /proc/cpuinfo' and look for 'sse2' in the flags section, or note that most modern i386 systems have SSE2 enabled by default.
    Affected if The system is i386/i686 with SSE2 support, which causes glibc to use the vulnerable SSE2-optimized memmove path

A system is affected if it runs on 32-bit x86 (i386/i686) architecture with glibc version 2.21 through 2.27 and has SSE2 support enabled, causing the vulnerable memmove implementation to be used.

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.

dbcve · scoped
Upgrade available Upgrade to a release after 2.27
Interim mitigation

Update glibc to version 2.28 or later where the overlapping memory check bug in the SSE2-optimized memmove was fixed.

Recommended fix High confidence

glibc 2.28 or later

  1. Upgrade glibc to version 2.28 or later. On Debian/Ubuntu systems: apt-get update && apt-get install libc6
  2. On RHEL/CentOS systems: yum update glibc
  3. On systems using package managers, ensure glibc is updated through standard package update mechanisms
  4. After updating, restart any services that depend on the updated glibc to ensure the new library is loaded
  5. Verify the fix by checking glibc version: ldd --version should show version 2.28 or later
Caveat Upgrading glibc can affect binary compatibility; ensure dependent applications are recompiled if needed. Major version jumps may introduce subtle behavioral changes.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Glibc Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing4.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,360
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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-2017-18269 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