CVE-2025-55152Public exploitNetwork attack vector

Service slowdown via forwarded-header regular expressions

Published Aug 9, 2025 · Updated Aug 11, 2025

Regular expression denial of service in oakserver Oak before 17.1.6 allows remote attackers to slow servers with crafted forwarding headers. With proxy mode enabled, Request.ips and URL protocol parsing pass unbounded x-forwarded-for and x-forwarded-proto values through an inefficient whitespace-comma expression, causing superlinear CPU work. Unauthenticated requests can degrade service when application code accesses the affected request properties; the published proof of concept demonstrates delay rather than a crash.

CVSS severity5.3
Medium
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Regular expression denial of service in oakserver Oak before 17.1.6 allows remote attackers to slow servers with crafted forwarding headers. With proxy mode enabled, Request.ips and URL protocol parsing pass unbounded x-forwarded-for and x-forwarded-proto values through an inefficient whitespace-comma expression, causing superlinear CPU work. Unauthenticated requests can degrade service when application code accesses the affected request properties; the published proof of concept demonstrates delay rather than a crash.

The record

CVE
CVE-2025-55152
Published
Aug 9, 2025
Updated
Aug 11, 2025
Vendor
oakserver
Product
Oak
Classifications
CWE-400, CWE-1333, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 9, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 11, 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=< 17.1.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

oakserver · Oakversion=< 17.1.6

Published CVSS scores

5.3GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
CWE-1333Inefficient Regular Expression Complexity
T1499.003Application Exhaustion Flood

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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