CVE-2001-0977: slapd in OpenLDAP 1.x before 1.2.12, and 2.x before 2.0.8, allows remote attackers to cause a denial of servic

This month

MEDIUM 5.0WATCHLISTDOWNGRADEDOWNGRADEMITIGATE

CVE-2001-0977 is a medium-severity flaw (CVSS 5.0) affecting mandrake single network firewall, openldap, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

slapd in OpenLDAP 1.x before 1.2.12, and 2.x before 2.0.8, allows remote attackers to cause a denial of service (crash) via an invalid Basic Encoding Rules (BER) length field.

Why this priority

EPSS top 9%: very likely to be exploited
On your watchlist

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

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	4.1% (top 9%)
CISA exploited list	No
Published	2001-07-16
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: debian · mandrakesoft · openldap · redhat

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

Am I affected?

Timeline

2001-07-16 04:00 UTCPublished CVE record published
2026-06-16 21:55 UTCUpdated Record last modified

mandrakesoft mandrake single network firewall DOWNGRADE

Affected: 7.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.2

1. Check installed version

apt-cache policy mandrake-single-network-firewall || rpm -q mandrake-single-network-firewall || mandrake-single-network-firewall --version

2. No fixed release: DOWNGRADE to a release before 7.2 (Debian / Ubuntu)

apt-cache madison mandrake-single-network-firewall sudo apt install mandrake-single-network-firewall=<VERSION_BEFORE_7.2> sudo apt-mark hold mandrake-single-network-firewall

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

dnf --showduplicates list mandrake-single-network-firewall sudo dnf downgrade mandrake-single-network-firewall-<VERSION_BEFORE_7.2> sudo dnf versionlock add mandrake-single-network-firewall

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.

openldap openldap DOWNGRADE

Affected: 1.0 · 1.0.1 · 1.0.2 · 1.0.3 · 1.1 · 1.1.1 · 1.1.2 · 1.1.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.0 (Debian / Ubuntu)

apt-cache madison openldap sudo apt install openldap=<VERSION_BEFORE_1.0> sudo apt-mark hold openldap

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

dnf --showduplicates list openldap sudo dnf downgrade openldap-<VERSION_BEFORE_1.0> sudo dnf versionlock add openldap

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: 2.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.2

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.

mandrakesoft mandrake linux MITIGATE

Affected: 7.1 · 7.2 · 8.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.1

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 corporate server 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.

redhat linux MITIGATE

Affected: 6.2 · 7.0 · 7.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 6.2

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.

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-2001-0977?

mandrake single network firewall: downgrade or apply the listed mitigation; openldap: 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-2001-0977 being exploited?

CVE-2001-0977 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-2001-0977 affect?

CVE-2001-0977 affects mandrake single network firewall, openldap, debian linux. Severity is medium (CVSS 5.0). slapd in OpenLDAP 1.x before 1.2.12, and 2.x before 2.0.8, allows remote attackers to cause a denial of service (crash) via an invalid Basic Encoding Rules (BER) length field.

How urgent is CVE-2001-0977?

Priority 45/100. EPSS top 9%: very likely to be exploited; On your watchlist

Software pages

Debian vulnerabilities · OpenLDAP vulnerabilities

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References

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