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Debian LinuxOperating system · Debian

CVE-2018-11490

HIGH · 8.8 CVSS v3.1 Published 2018-05-26
Fix available
A fix is available. Upgrade to after 3.1.1 or later.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges

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 DGifDecompressLine function in dgif_lib.c in GIFLIB (possibly version 3.0.x), as later shipped in cgif.c in sam2p 0.49.4, has a heap-based buffer overflow because a certain "Private->RunningCode - 2" array index is not checked. This will lead to a denial of service or possibly unspecified other impact.

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

Heap-based buffer overflow in GIFLIB's DGifDecompressLine function in dgif_lib.c (also affecting sam2p 0.49.4). The vulnerability occurs because the array index 'Private->RunningCode - 2' is not validated before use, allowing out-of-bounds memory access during GIF decompression.

MitigationUpdate to a patched version of GIFLIB that adds proper bounds checking on the RunningCode index before array access. For sam2p, update to version 0.49.5 or later if available, or apply the same bounds-checking fix to the cgif.c code.

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
Debian LinuxOperating system
Affected:= 10.0
Ubuntu LinuxOperating system
Affected:= 16.04= 18.04= 19.04
GiflibApplication
Affected:>= 3.0, <= 3.1.1
Sam2pApplication
Affected:= 0.49.4

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
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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 if GIFLIB library is installed and its version
    Run 'dpkg -l | grep giflib' (Debian/Ubuntu) or 'rpm -qa | grep giflib' (RHEL/CentOS) to list installed giflib packages, or check the shared library version with 'ldconfig -p | grep gif' and then 'giflib-config --version' if available
    Affected if The installed version is between 3.0 and 3.1.1 inclusive (versions prior to the bounds-checking fix)
  2. Check if sam2p is installed and its version
    Run 'dpkg -l | grep sam2p' (Debian/Ubuntu) or 'rpm -qa | grep sam2p' (RHEL/CentOS) to list installed sam2p packages, or check 'sam2p --version' if the binary exists
    Affected if The installed sam2p version is exactly 0.49.4
  3. Identify applications or tools that link to the vulnerable giflib library
    Use 'ldd /path/to/binary | grep gif' or 'ldconfig -p | grep gif' to find executables that load libgif.so, or check for image processing tools that depend on giflib (such as ImageMagick, feh, or other GIF-handling utilities)
    Affected if Any application that uses the DGifDecompressLine function from an affected giflib version is potentially vulnerable when decompressing specially crafted GIF files
  4. Confirm the dgif_lib.c source code version if giflib is built from source
    Inspect the dgif_lib.c file in the source tree and search for the DGifDecompressLine function, specifically looking for the use of 'Private->RunningCode - 2' as an array index without bounds validation
    Affected if The source code lacks bounds checking on the RunningCode index before array access in the DGifDecompressLine function
  5. Check for GIF processing in server or web-facing applications
    Identify any web applications, image processing services, or automated tools that accept user-uploaded GIF files and use giflib or sam2p for decompression
    Affected if User-supplied GIF files can be processed by a vulnerable version of giflib or sam2p, triggering the heap buffer overflow

You are affected if giflib version 3.0 through 3.1.1 or sam2p version 0.49.4 is installed and processes untrusted GIF files, as the missing bounds check on the RunningCode index allows heap-based buffer overflow during decompression.

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 3.1.1
Interim mitigation

Update to a patched version of GIFLIB that adds proper bounds checking on the RunningCode index before array access. For sam2p, update to version 0.49.5 or later if available, or apply the same bounds-checking fix to the cgif.c code.

Fix this in Debian Linux Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
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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-2018-11490 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