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Cpp Httplib CVE-2020-11709

HIGH
Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') (CWE-74)
2020-04-12 cve@mitre.org
7.5
CVSS 3.1 · NVD
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Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Input neutralization, injection prevention
Impact

CVSS score of 7.5 (HIGH). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. Public proof-of-concept exploit code is available.

Exploit ScenarioDerived

This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the high-severity affected system.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 1.6% exploitation probability (EPSS)

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AnalysisAI

cpp-httplib through 0.5.8 does not filter \r\n in parameters passed into the set_redirect and set_header functions, which creates possibilities for CRLF injection and HTTP response splitting in some. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affects your stack

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Technical ContextAI · show details

This vulnerability is classified under CWE-74. cpp-httplib through 0.5.8 does not filter \r\n in parameters passed into the set_redirect and set_header functions, which creates possibilities for CRLF injection and HTTP response splitting in some specific contexts. Affected products include: Yhirose Cpp-Httplib. Version information: through 0.5.8.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

DescriptionNVD

cpp-httplib through 0.5.8 does not filter \r\n in parameters passed into the set_redirect and set_header functions, which creates possibilities for CRLF injection and HTTP response splitting in some specific contexts.

Threat Intelligence Overview

EPSS Score
1.6%
Top 26% exploitable
Exploit
POC
Public exploit code exists
Data Quality
3 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC Yes
EPSS 1.6%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
Poc
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact· derived
Medium

Priority Score

60
Low Medium High Critical
KEV: 0
EPSS: +2
CVSS: +38
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Code Injection CRITICAL

Code injection occurs when an application accepts user input and passes it directly into a language interpreter or evaluator without proper sanitization.

Affected Products (CPE)NVD

cpe:2.3:a:yhirose:cpp-httplib:*:*:*:*:*:*:*:*
CVE-2025-66570 CRITICAL POC
10.0 Dec 05

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.27.0, a vulnerability allow

CVE-2025-53628 HIGH POC
8.8 Jul 10

CVE-2025-53628 is a memory exhaustion vulnerability in cpp-httplib versions prior to 0.20.1 that allows unauthenticated

CVE-2025-46728 HIGH POC
7.5 May 06

cpp-httplib is a C++ header-only HTTP/HTTPS server and client library. Rated high severity (CVSS 7.5), this vulnerabilit

CVE-2025-52887 HIGH POC
7.5 Jun 26

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. In version 0.21.0, when many http head

CVE-2025-53629 HIGH POC
7.5 Jul 10

CVE-2025-53629 is a Denial of Service vulnerability in cpp-httplib versions prior to 0.23.0 that allows unauthenticated

CVE-2026-22776 HIGH POC
7.5 Jan 12

cpp-httplib versions prior to 0.30.1 are vulnerable to denial of service attacks due to insufficient validation of decom

CVE-2026-28435 HIGH POC
7.5 Mar 04

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. [CVSS 7.5 HIGH]

CVE-2026-21428 HIGH POC
7.5 Jan 01

Cpp-Httplib versions up to 0.30.0 contains a vulnerability that allows attackers to add extra headers, modify request bo

CVE-2026-45372 CRITICAL
9.9 May 29

HTTP response/header injection in cpp-httplib server versions prior to 0.44.0 allows remote unauthenticated attackers to

CVE-2026-29076 MEDIUM POC
5.9 Mar 07

Remote denial of service in cpp-httplib prior to version 0.37.0 allows unauthenticated attackers to crash server process

CVE-2025-66577 MEDIUM POC
5.3 Dec 05

A security vulnerability in cpp-httplib (CVSS 5.3) that allows attacker-controlled http headers. Risk factors: public Po

CVE-2026-28434 MEDIUM POC
5.3 Mar 04

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. [CVSS 5.3 MEDIUM]

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