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NVD / CVE Program· CNA mitre

CVE-2000-0453: XFree86 3.3.x and 4.0 allows a user to cause a denial of service via a negative counter value in a malformed TCP packet that is sent to port…

MediumCVSS 5.0 · v2.0—Proof of concept No fix recorded

Noroxi assessment

Priority: Monitor (action score 21/100)

  • Public proof-of-concept code exists (Exploit-DB); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 2.9% (FIRST EPSS); higher than 87.4% of all records.
  • No special conditions are required; it is repeatable.
  • According to the record, no fixed version is available yet.

Low priority for now. Update when a fix is released; follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

XFree86 3.3.x and 4.0 allows a user to cause a denial of service via a negative counter value in a malformed TCP packet that is sent to port 6000.

Published
May 18, 2000
Updated
Jun 16, 2026
EPSS
2.9% · 87th percentile
CWE
—

Report tools

JSON

Action score

21

Monitor

Low priority for now.

CVSS
20 / 40 · 5.0 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 2.9%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2000-0453

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
xfree86 projectx11r6

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • xfree86 project x11r63.3.5
  • xfree86 project x11r63.3.6
  • xfree86 project x11r64.0

Same product

xfree86 project: all records

Other highest-scoring records for the same primary product.

  • CVE-2004-0084Buffer overflow in the ReadFontAlias function in XFree86 4.1.0 to 4.3.0, when using the CopyISOLatin1Lowered function, allows local or…
    47Plan
  • CVE-2004-0083Buffer overflow in ReadFontAlias from dirfile.c of XFree86 4.1.0 through 4.3.0 allows local users and remote attackers to execute arbitrary…
    46Plan
  • CVE-2002-1510xdm, with the authComplain variable set to false, allows arbitrary attackers to connect to the X server if the xdm auth directory does not…
    41Plan

Published before and after this one in the same product

  • ← EarlierCVE-1999-0433Mar 21, 1999 · XFree86 startx command is vulnerable to a symlink attack, allowing local users to create files in restricted directories, possibly allowing…
    18Monitor
  • ← EarlierCVE-2000-0285Apr 16, 2000 · Buffer overflow in XFree86 3.3.x allows local users to execute arbitrary commands via a long -xkbmap parameter.
    28Monitor
  • Later →CVE-2001-1086Jul 4, 2001 · XDM in XFree86 3.3 and 3.3.3 generates easily guessable cookies using gettimeofday() when compiled with the HasXdmXauth option, which…
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Exploit-DB entry ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Exploit-DB entrydos2000-05-18

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. First PoCsame day
  3. TodayNov 15, 2026+9678 d

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
P · the service can be disrupted
Attack complexity
Low
Confidentiality impact
None
Integrity impact
None
Availability impact
P

Weakness class (CWE)

—

CVSS vector

AV:N/AC:L/Au:N/C:N/I:N/A:P

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records