CVE-2002-0002: Format string vulnerability in stunnel before 3.22 when used in client mode for (1) smtp, (2) pop, or (3) nntp

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HIGH 7.5WATCHLISTDOWNGRADEMITIGATEMITIGATE

CVE-2002-0002 is a high-severity flaw (CVSS 7.5) affecting stunnel, secure linux, mandrake linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Format string vulnerability in stunnel before 3.22 when used in client mode for (1) smtp, (2) pop, or (3) nntp allows remote malicious servers to execute arbitrary code.

Why this priority

High severity
EPSS top 7%: very likely to be exploited
Public exploit reference
On your watchlist

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

Risk facts

CVSS score	7.5 (High)
EPSS exploit chance	5.3% (top 7%)
CISA exploited list	No
Published	2002-01-31
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: engardelinux · mandrakesoft · redhat · stunnel

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

Am I affected?

Timeline

2002-01-31 05:00 UTCPublished CVE record published
2026-06-16 21:56 UTCUpdated Record last modified

stunnel stunnel DOWNGRADE

Affected: 3.3 · 3.4a · 3.7 · 3.8 · 3.9 · 3.10 · 3.11 · 3.12

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.3

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 3.3 (Debian / Ubuntu)

apt-cache madison stunnel sudo apt install stunnel=<VERSION_BEFORE_3.3> sudo apt-mark hold stunnel

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

dnf --showduplicates list stunnel sudo dnf downgrade stunnel-<VERSION_BEFORE_3.3> sudo dnf versionlock add stunnel

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.

engardelinux secure linux MITIGATE

Affected: 1.0.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.0.1

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.

mandrakesoft mandrake linux MITIGATE

Affected: 8.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.1

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.

redhat linux MITIGATE

Affected: 7.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.2

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.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: STunnel 3.x - Client Negotiation Protocol Format String

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-2002-0002?

stunnel: downgrade or apply the listed mitigation; secure linux: mitigate or apply the listed mitigation; mandrake linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2002-0002 being exploited?

CVE-2002-0002 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-2002-0002 affect?

CVE-2002-0002 affects stunnel, secure linux, mandrake linux. Severity is high (CVSS 7.5). Format string vulnerability in stunnel before 3.22 when used in client mode for (1) smtp, (2) pop, or (3) nntp allows remote malicious servers to execute arbitrary code.

How urgent is CVE-2002-0002?

Priority 59/100. High severity; EPSS top 7%: very likely to be exploited; Public exploit reference; On your watchlist

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References

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