CVE-2025-6494Public exploit

Application crash via fixed-size hashmap string copies

Published Jun 22, 2025 · Updated Jun 30, 2025

Heap-based buffer overflow in Nokogiri commit c29c920907366cb74af13b4dc2230e9c9e23b833 allows local users to crash applications via crafted HTML. Gumbo's string set passes variable-length attribute-name bytes as fixed eight-byte hashmap items, causing strcmp to read beyond the allocation during duplicate-attribute lookup. The affected code exists only in an unreleased source commit, so published Nokogiri gems are not exposed; a locally built C Gumbo implementation must parse the input.

CVSS severity3.3
Low
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in Nokogiri commit c29c920907366cb74af13b4dc2230e9c9e23b833 allows local users to crash applications via crafted HTML. Gumbo's string set passes variable-length attribute-name bytes as fixed eight-byte hashmap items, causing strcmp to read beyond the allocation during duplicate-attribute lookup. The affected code exists only in an unreleased source commit, so published Nokogiri gems are not exposed; a locally built C Gumbo implementation must parse the input.

The record

CVE
CVE-2025-6494
Published
Jun 22, 2025
Updated
Jun 30, 2025
Vendor
Sparkle Motion
Product
Nokogiri
Classifications
CWE-122, CWE-119, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 22, 2025CVE publishedPublication date reported by the CVE source.
  2. Jun 30, 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=c29c920907366cb74af13b4dc2230e9c9e23b833

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Sparkle Motion · Nokogiriversion=c29c920907366cb74af13b4dc2230e9c9e23b833

Published CVSS scores

1.9VulDBCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
1.7VulDBAV:L/AC:L/Au:S/C:N/I:N/A:P
3.3VulDBCVSS:3.1/AV:L/AC:L/PR:L/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow
CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
T1499Endpoint Denial of Service

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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