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NVD / CVE Program· CNA mitre

CVE-2004-0751: The char_buffer_read function in the mod_ssl module for Apache 2.x, when using reverse proxying to an SSL server, allows remote attackers to…

MediumCVSS 5.0 · v2.0—Proof of concept Fix available

Noroxi assessment

Priority: Plan (action score 42/100)

  • 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: 72.3% (FIRST EPSS); higher than 99.4% of all records.
  • No special conditions are required; it is repeatable.
  • Fixed version: apache2 (Debian:12) 2.0.50-11; httpd (Red Hat:enterprise_linux:3::as) 0:2.0.46-40.ent; httpd-debuginfo (Red Hat:enterprise_linux:3::as) 0:2.0.46-40.ent.

Add it to your regular patch cycle. Upgrade to apache2 (Debian:12) 2.0.50-11; httpd (Red Hat:enterprise_linux:3::as) 0:2.0.46-40.ent; httpd-debuginfo (Red Hat:enterprise_linux:3::as) 0:2.0.46-40.ent or later.

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

The char_buffer_read function in the mod_ssl module for Apache 2.x, when using reverse proxying to an SSL server, allows remote attackers to cause a denial of service (segmentation fault).

Published
Oct 20, 2004
Updated
Jun 16, 2026
EPSS
72.3% · 99th percentile
CWE
—

Report tools

JSON

Action score

42

Plan

Add it to your regular patch cycle.

CVSS
20 / 40 · 5.0 / 10
CISA KEV
0 / 30 · Not listed
EPSS
22 / 30 · 72.3%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

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

Follow CVE-2004-0751

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?

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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
apachehttp server

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When you'll hear from us

  • when a new CVE affecting this product is published
  • when a record in your stack enters KEV or is weaponized

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits every 10 minutes on paid plans, on the hour on the free plan.

Is Apache HTTP Server on your server exposed to the internet?Run a port scan

Your free account also gets you

  • CVE alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools, at most 30 a day (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every Monday

Is Apache HTTP Server on your server exposed to the internet?

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Affected versions

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

  • apache http server2.0.44 and later · before 2.0.51

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12apache2before 2.0.50-112.0.50-11
Red Hat:enterprise_linux:3::ashttpdbefore 0:2.0.46-40.ent0:2.0.46-40.ent
Red Hat:enterprise_linux:3::ashttpd-debuginfobefore 0:2.0.46-40.ent0:2.0.46-40.ent
Red Hat:enterprise_linux:3::ashttpd-develbefore 0:2.0.46-40.ent0:2.0.46-40.ent
Red Hat:enterprise_linux:3::asmod_sslbefore 1:2.0.46-40.ent1:2.0.46-40.ent

Same product

apache: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-42013Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773)KEV
    99Now
  • CVE-2021-41773Path traversal and file disclosure vulnerability in Apache HTTP Server 2.4.49KEV
    99Now
  • CVE-2024-38475Apache HTTP Server weakness in mod_rewrite when first segment of substitution matches filesystem path.KEV
    96Now

Published before and after this one in the same product

  • ← EarlierCVE-2004-0747Oct 20, 2004 · Buffer overflow in Apache 2.0.50 and earlier allows local users to gain apache privileges via a .htaccess file that causes the overflow…
    31Monitor
  • ← EarlierCVE-2004-0748Oct 20, 2004 · mod_ssl in Apache 2.0.50 and earlier allows remote attackers to cause a denial of service (CPU consumption) by aborting an SSL connection…
    27Monitor
  • Later →CVE-2004-0786Oct 20, 2004 · The IPv6 URI parsing routines in the apr-util library for Apache 2.0.50 and earlier allow remote attackers to cause a denial of service…
    27Monitor

Remediation

Which version to upgrade to

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

Product / packageFixed versionSource
debian:apache22.0.50-11 · Debian:12Package registry (OSV)
red hat:httpd0:2.0.46-40.ent · Red Hat:enterprise_linux:3::asPackage registry (OSV)
red hat:httpd-debuginfo0:2.0.46-40.ent · Red Hat:enterprise_linux:3::asPackage registry (OSV)
red hat:httpd-devel0:2.0.46-40.ent · Red Hat:enterprise_linux:3::asPackage registry (OSV)
red hat:mod_ssl1:2.0.46-40.ent · Red Hat:enterprise_linux:3::asPackage registry (OSV)

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 entrydos2004-09-10

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. First PoC-40 d
  2. Published
  3. TodayNov 15, 2026+8061 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Not on record for this CVE: 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 (19 more)

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

All records