CVE-2002-0851: Format string vulnerability in ISDN Point to Point Protocol (PPP) daemon (ipppd) in the ISDN4Linux (i4l) packa

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HIGH 7.2WATCHLISTDOWNGRADE

CVE-2002-0851 is a high-severity flaw (CVSS 7.2) affecting isdn4linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Format string vulnerability in ISDN Point to Point Protocol (PPP) daemon (ipppd) in the ISDN4Linux (i4l) package allows local users to gain root privileges via format strings in the device name command line argument, which is not properly handled in a call to syslog.

Why this priority

High severity
Public exploit reference
On your watchlist

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

Risk facts

CVSS score	7.2 (High)
EPSS exploit chance	1.1% (top 36%)
CISA exploited list	No
Published	2002-09-05
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: isdn4linux

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

Am I affected?

Timeline

2002-09-05 04:00 UTCPublished CVE record published
2026-06-16 21:58 UTCUpdated Record last modified

isdn4linux isdn4linux DOWNGRADE

Affected: 3.1_pre1

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.1_pre1

1. Check installed version

apt-cache policy isdn4linux || rpm -q isdn4linux || isdn4linux --version

2. No fixed release: DOWNGRADE to a release before 3.1_pre1 (Debian / Ubuntu)

apt-cache madison isdn4linux sudo apt install isdn4linux=<VERSION_BEFORE_3.1_pre1> sudo apt-mark hold isdn4linux

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

dnf --showduplicates list isdn4linux sudo dnf downgrade isdn4linux-<VERSION_BEFORE_3.1_pre1> sudo dnf versionlock add isdn4linux

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.

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: ISDN4Linux 3.1 - IPPPD Device String SysLog Format String (1)
Exploit-DB: ISDN4Linux 3.1 - IPPPD Device String SysLog Format String (2)

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-2002-0851?

isdn4linux: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2002-0851 being exploited?

CVE-2002-0851 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-2002-0851 affect?

CVE-2002-0851 affects isdn4linux. Severity is high (CVSS 7.2). Format string vulnerability in ISDN Point to Point Protocol (PPP) daemon (ipppd) in the ISDN4Linux (i4l) package allows local users to gain root privileges via format strings in the device name command line argument, which is not properly h

How urgent is CVE-2002-0851?

Priority 51/100. High severity; Public exploit reference; On your watchlist

References

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