CVE-2025-63655Public exploitNetwork attack vector

Unauthenticated server crash via malformed Range header

Published Jan 29, 2026 · Updated Jan 29, 2026

NULL pointer dereference in Monkey through commit f37e984 allows remote attackers to crash the HTTP server with a crafted Range header. In mk_http_range_parse, a Range value shaped like bytes\0-= makes mk_string_copy_substr return NULL, which the function passes to atol. No authentication or user interaction is required; successful exploitation terminates the server process and interrupts HTTP service.

CVSS severity7.5
High
EPSS probability7.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Monkey through commit f37e984 allows remote attackers to crash the HTTP server with a crafted Range header. In mk_http_range_parse, a Range value shaped like bytes\0-= makes mk_string_copy_substr return NULL, which the function passes to atol. No authentication or user interaction is required; successful exploitation terminates the server process and interrupts HTTP service.

The record

CVE
CVE-2025-63655
Published
Jan 29, 2026
Updated
Jan 29, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-476, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 29, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5CISA-ADPCVSS: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-476NULL Pointer Dereference
T1499.004Application or System Exploitation 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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