CVE-2025-0825Network attack vector

Response splitting via null-prefixed CRLF bypass

Published Feb 4, 2025 · Updated May 23, 2025

HTTP response splitting in Yuji Hirose cpp-httplib 0.17.3 through 0.18.3 allows remote attackers to inject response headers. Request::set_header, Response::set_header, and Response::set_redirect accept null-prefixed CRLF sequences because the prior has_crlf validation misses them. Exploitation requires an embedding application to pass attacker-controlled data to these operations, enabling altered responses or script execution in a recipient browser.

CVSS severity6.9
Medium
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP response splitting in Yuji Hirose cpp-httplib 0.17.3 through 0.18.3 allows remote attackers to inject response headers. Request::set_header, Response::set_header, and Response::set_redirect accept null-prefixed CRLF sequences because the prior has_crlf validation misses them. Exploitation requires an embedding application to pass attacker-controlled data to these operations, enabling altered responses or script execution in a recipient browser.

The record

CVE
CVE-2025-0825
Published
Feb 4, 2025
Updated
May 23, 2025
Vendor
Yuji Hirose
Product
cpp-httplib
Classifications
CWE-113, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 4, 2025CVE publishedPublication date reported by the CVE source.
  2. May 23, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=v0.17.3 <=v0.18.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Yuji Hirose · cpp-httplibversion=v0.17.3 <=v0.18.3

Published CVSS scores

6.9CheckmarxCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-113Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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