CVE-2002-1091: Netscape 6.2.3 and earlier, and Mozilla 1.0.1, allow remote attackers to corrupt heap memory and execute arbit

This month

HIGH 7.5DOWNGRADEDOWNGRADEDOWNGRADE

CVE-2002-1091 is a high-severity flaw (CVSS 7.5) affecting mozilla, navigator, opera web browser. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Netscape 6.2.3 and earlier, and Mozilla 1.0.1, allow remote attackers to corrupt heap memory and execute arbitrary code via a GIF image with a zero width.

Why this priority

High severity
EPSS top 9%: very likely to be exploited
Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
EPSS exploit chance	4.3% (top 9%)
CISA exploited list	No
Published	2002-10-04
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: mozilla · netscape · opera software

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2002-10-04 04:00 UTCPublished CVE record published
2026-06-16 21:58 UTCUpdated Record last modified

mozilla mozilla DOWNGRADE

Affected: 0.9.5 · 0.9.6 · 0.9.7 · 0.9.8 · 0.9.9 · 1.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.9.5

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.9.5 (Debian / Ubuntu)

apt-cache madison mozilla sudo apt install mozilla=<VERSION_BEFORE_0.9.5> sudo apt-mark hold mozilla

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

dnf --showduplicates list mozilla sudo dnf downgrade mozilla-<VERSION_BEFORE_0.9.5> sudo dnf versionlock add mozilla

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.

netscape navigator DOWNGRADE

Affected: 6.2 · 6.2.1 · 6.2.2 · 6.2.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 6.2

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 6.2 (Debian / Ubuntu)

apt-cache madison navigator sudo apt install navigator=<VERSION_BEFORE_6.2> sudo apt-mark hold navigator

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

dnf --showduplicates list navigator sudo dnf downgrade navigator-<VERSION_BEFORE_6.2> sudo dnf versionlock add navigator

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.

opera software opera web browser DOWNGRADE

Affected: 5.12 · 6.0 · 6.0.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.12

1. Check installed version

apt-cache policy opera-web-browser || rpm -q opera-web-browser || opera-web-browser --version

2. No fixed release: DOWNGRADE to a release before 5.12 (Debian / Ubuntu)

apt-cache madison opera-web-browser sudo apt install opera-web-browser=<VERSION_BEFORE_5.12> sudo apt-mark hold opera-web-browser

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

dnf --showduplicates list opera-web-browser sudo dnf downgrade opera-web-browser-<VERSION_BEFORE_5.12> sudo dnf versionlock add opera-web-browser

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.

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-2002-1091?

mozilla: downgrade or apply the listed mitigation; navigator: downgrade or apply the listed mitigation; opera web browser: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2002-1091 being exploited?

CVE-2002-1091 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-2002-1091 affect?

CVE-2002-1091 affects mozilla, navigator, opera web browser. Severity is high (CVSS 7.5). Netscape 6.2.3 and earlier, and Mozilla 1.0.1, allow remote attackers to corrupt heap memory and execute arbitrary code via a GIF image with a zero width.

How urgent is CVE-2002-1091?

Priority 54/100. High severity; EPSS top 9%: very likely to be exploited; Public exploit reference

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References

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