CVE-2003-0899

Q: How do I fix CVE-2003-0899?

Upgrade thttpd to 2.23 or later.

Q: Is CVE-2003-0899 being actively exploited?

Not that we know of. CVE-2003-0899 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 21.7% is the estimated probability that it will be exploited in the next 30 days. That is higher than 97% of all scored CVEs.

Q: How severe is CVE-2003-0899?

CVE-2003-0899 has a CVSS v3 base score of 9.8, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

Q: What does CVE-2003-0899 affect?

Published advisories record a fix for thttpd (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

CRITICALEPSS 97th pctl

9.8

CVSS v3

NVD

Description

Buffer overflow in defang in libhttpd.c for thttpd 2.21 to 2.23b1 allows remote attackers to execute arbitrary code via requests that contain '<' or '>' characters, which trigger the overflow when the characters are expanded to "<" and ">" sequences.

CWE-131

How to fix

Remediation Available

thttpdNVD

Affected:>= 2.21, < 2.23Fixed in:2.23CVE-2003-0899derived from NVD

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

21.68%probability of exploitation in 30 days

97thpercentile

Very high risk: more likely to be exploited than 97% of all known CVEs.

References

Patch2

Exploit1

marc.info

Third-Party Advisory1

exchange.xforce.ibmcloud.com

Other references3

Related Vulnerabilities

Other CWE-131 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-36824	High	7.4	77%	-	Fix
CVE-2020-8450	High	7.3	72%	-	Fix
CVE-2020-6113	High	7.8	69%	-	-
CVE-2026-42945	Critical	8.1	66%	-	Fix
CVE-2020-6116	High	7.8	28%	-	-
CVE-2005-3120	Critical	9.8	23%	-	Fix

Common questions

How do I fix CVE-2003-0899?

Upgrade thttpd to 2.23 or later.

Is CVE-2003-0899 being actively exploited?

Not that we know of. CVE-2003-0899 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 21.7% is the estimated probability that it will be exploited in the next 30 days. That is higher than 97% of all scored CVEs.

How severe is CVE-2003-0899?

CVE-2003-0899 has a CVSS v3 base score of 9.8, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2003-0899 affect?

Published advisories record a fix for thttpd (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-16.