CVE-2018-11490: The DGifDecompressLine function in dgif_lib.c in GIFLIB (possibly version 3.0.x), as later shipped in cgif.c i

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HIGH 8.8WATCHLISTUPGRADEDOWNGRADEMITIGATE

CVE-2018-11490 is a high-severity flaw (CVSS 8.8) affecting giflib, sam2p, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	2.4% (top 16%)
CISA exploited list	No
Weakness	CWE-129, CWE-787
Published	2018-05-26
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: canonical · debian · giflib project · sam2p project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2018-05-26 18:29 UTCPublished CVE record published
2026-06-17 01:36 UTCUpdated Record last modified

giflib project giflib UPGRADE

Affected: >= 3.0 and <= 3.1.1

Fixed in: newer than 3.1.1

Safe to downgrade to: a release before 3.0

1. Check installed version

apt-cache policy giflib || rpm -q giflib || giflib --version

2. UPGRADE to newer than 3.1.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade giflib

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade giflib

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 3.0 (Debian / Ubuntu)

apt-cache madison giflib sudo apt install giflib=<VERSION_BEFORE_3.0> sudo apt-mark hold giflib

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list giflib sudo dnf downgrade giflib-<VERSION_BEFORE_3.0> sudo dnf versionlock add giflib

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

sam2p project sam2p DOWNGRADE

Affected: 0.49.4

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.49.4

1. Check installed version

apt-cache policy sam2p || rpm -q sam2p || sam2p --version

2. No fixed release: DOWNGRADE to a release before 0.49.4 (Debian / Ubuntu)

apt-cache madison sam2p sudo apt install sam2p=<VERSION_BEFORE_0.49.4> sudo apt-mark hold sam2p

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list sam2p sudo dnf downgrade sam2p-<VERSION_BEFORE_0.49.4> sudo dnf versionlock add sam2p

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

debian debian linux MITIGATE

Affected: 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

canonical ubuntu linux MITIGATE

Affected: 16.04 · 18.04 · 19.04

Fixed in: no fixed release known

Safe to downgrade to: a release before 16.04

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2018-11490?

giflib: upgrade to newer than 3.1.1; sam2p: downgrade or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2018-11490 being exploited?

CVE-2018-11490 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2018-11490 affect?

CVE-2018-11490 affects giflib, sam2p, debian linux. Severity is high (CVSS 8.8). 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 wil

How urgent is CVE-2018-11490?

Priority 57/100. High severity; On your watchlist

Software pages

Ubuntu vulnerabilities · Debian vulnerabilities

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CVE-2024-45993 MEDIUM 6.5 DOWNGRADE Giflib Project v5.2.2 is vulnerable to a heap buffer overflow via gif2rgb.
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References

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