CVE-2026-28435Public exploitNetwork attack vector

Denial of service via unchecked streaming decompression

Published Mar 4, 2026 · Updated Mar 4, 2026

Denial of service in Yuji Hirose cpp-httplib before 0.35.0 allows remote attackers to exhaust CPU or memory via compressed requests. In httplib.h, prepare_content_receiver counts compressed socket bytes against payload_max_length_ but forwards unbounded decompressed chunks to HandlerWithContentReader. Exposure requires server-side streaming handlers, decompression support, and reliance on set_payload_max_length_; oversized expansion exhausts resources and interrupts service under load.

CVSS severity7.5
High
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Yuji Hirose cpp-httplib before 0.35.0 allows remote attackers to exhaust CPU or memory via compressed requests. In httplib.h, prepare_content_receiver counts compressed socket bytes against payload_max_length_ but forwards unbounded decompressed chunks to HandlerWithContentReader. Exposure requires server-side streaming handlers, decompression support, and reliance on set_payload_max_length_; oversized expansion exhausts resources and interrupts service under load.

The record

CVE
CVE-2026-28435
Published
Mar 4, 2026
Updated
Mar 4, 2026
Vendor
Yuji Hirose
Product
cpp-httplib
Classifications
CWE-409, CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 4, 2026Record 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=< 0.35.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Yuji Hirose · cpp-httplibversion=< 0.35.0

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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 exploitPublished

Weakness, pattern, technique

CWE-409Improper Handling of Highly Compressed Data (Data Amplification)
CWE-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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