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CVE-2003-0899

53
FAUCET Score

CVE-2003-0899 describes a critical buffer overflow vulnerability in the 'defang' function of libhttpd.c within thttpd versions 2.21 to 2.23b1, affecting the acme thttpd web server. This flaw allows remote attackers to execute arbitrary code by sending requests containing '<' or '>' characters, which are expanded into longer HTML entities, leading to the overflow. With a CVSS score of 9.8 (CRITICAL), this vulnerability is easily exploitable over the network with low attack complexity and no user interaction, resulting in complete compromise of confidentiality, integrity, and availability. While not listed in CISA's KEV catalog, proof-of-concept exploit code is publicly available on ExploitDB, and it has garnered significant community discussion, indicating its potential for active exploitation.

Impacted Technologies

VendorProductVersion(s)CPE
>= 2.21, < 2.23CPE matchmatch criteria
cpe:2.3:a:acme:thttpd:*:*:*:*:*:*:*:*
2.23CPE matchmatch criteria
cpe:2.3:a:acme:thttpd:2.23:-:*:*:*:*:*:*
2.23CPE matchmatch criteria
cpe:2.3:a:acme:thttpd:2.23:b1:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
21.68%
Probability of exploitation in next 30 days
EPSS Percentile
97.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-24
Model: v2026.06.15
ExploitDB: EDB-23306 · Oct 27, 2003
This CVE's current EPSS score of 0.2168 is in the 94th percentile among its peer group of 36,821 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

marc.info
ExploitMailing List
secunia.com / advisories/10092
Broken LinkPatchVendor Advisory
exchange.xforce.ibmcloud.com / vulnerabilities/13530
Third Party AdvisoryVDB Entry
debian.org / security/2003/dsa-396
Broken Link
osvdb.org / 2729
Broken Link
securityfocus.com / bid/8906
Broken LinkExploitPatchThird Party AdvisoryVDB Entry
texonet.com / advisories/TEXONET-20030908.txt
Broken LinkURL Repurposed