CVE-2025-6490VulnerabilityPublished 22 Jun 2025Updated 30 Jun 2025

CVE-2025-6490: sparklemotion nokogiri · Heap-based Buffer Overflow

Affects sparklemotion nokogiriSource CVE Database V5

Not known to be exploited · CVSS 4.8 Medium.

Data as of 26 Oct 2026, 08:30 UTC

CVSS 4.0 base score

4.8Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS: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

Base metrics

Attack Vector: Local
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Threat metrics

Exploit Maturity: POC

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.
Exploit Maturity: POC: Based on threat intelligence sources each of the following must apply: · Proof-of-concept is publicly available · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 22 Jun 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

AI-suggested

1. Immediate upgrade: Organizations should upgrade Nokogiri to a version beyond 1.18.7 where this vulnerability is patched. 2. Restrict local access: Limit user and process permissions to only those necessary for running Nokogiri-dependent applications to reduce the risk of local exploitation. 3. Input validation: Implement strict validation and sanitization of XML/HTML inputs before parsing to minimize malformed or malicious data triggering the overflow. 4. Application sandboxing: Run Nokogiri-dependent processes in isolated environments or containers to contain potential exploitation impact. 5. Monitoring and detection: Deploy host-based intrusion detection systems (HIDS) and monitor application logs for abnormal crashes or memory errors indicative of exploitation attempts. 6. Code review: Audit custom code interfacing with Nokogiri to ensure safe usage patterns and avoid passing untrusted data without checks. 7. Incident response readiness: Prepare response plans for potential exploitation scenarios, including forensic analysis and system recovery procedures. These steps go beyond generic advice by focusing on local access control, input validation, and containment strategies tailored to the nature of the vulnerability.

Description

A vulnerability was found in sparklemotion nokogiri c29c920907366cb74af13b4dc2230e9c9e23b833 and classified as problematic. This issue affects the function hashmap_set_with_hash of the file gumbo-parser/src/hashmap.c. The manipulation leads to heap-based buffer overflow. An attack has to be approached locally. The exploit has been disclosed to the public and may be used. The real existence of this vulnerability is still doubted at the moment. The identifier of the patch is ada4708e5a67114402cd3feb70a4e1d1d7cf773a. It is recommended to apply a patch to fix this issue. The project maintainer explains that the affected code was merged into the main branch but the commit never appeared in an official release.

Impact

For European organizations, the impact of CVE-2025-6490 depends largely on the extent of Nokogiri usage within their software stacks. Organizations running Ruby applications that parse XML or HTML locally with affected Nokogiri versions are at risk of heap-based buffer overflow exploitation. This could lead to application crashes, denial of service, or potentially arbitrary code execution if an attacker can leverage the overflow to execute malicious payloads. The requirement for local access limits remote exploitation, but insider threats, compromised user accounts, or malicious local scripts could trigger the vulnerability. Sectors with high reliance on Ruby applications, such as financial services, e-commerce, and government agencies, may face operational disruptions or data integrity issues if exploited. Additionally, organizations processing sensitive XML/HTML data locally could see confidentiality and integrity impacts if the vulnerability is chained with other exploits. The medium CVSS score reflects moderate risk, but the public disclosure of exploit details elevates urgency for mitigation. European entities with compliance obligations under GDPR must consider potential data breach implications if exploitation leads to unauthorized data access or system compromise.

Summary

CVE-2025-6490 is a heap-based buffer overflow vulnerability identified in the Nokogiri library, versions up to 1.18.7, developed by the sparklemotion project. Nokogiri is a widely used Ruby gem for parsing XML and HTML documents, often embedded in various web applications and services. The vulnerability specifically resides in the function hashmap_set_with_hash within the gumbo-parser component's source file hashmap.c. This function is responsible for managing hash map entries during parsing operations. Due to improper handling of input data, an attacker with local access can manipulate the function's behavior to cause a heap-based buffer overflow, potentially leading to memory corruption. This can result in application crashes or, in some cases, arbitrary code execution. The vulnerability requires local access with low privileges (PR:L) but does not require user interaction (UI:N) or authentication (AT:N). The CVSS 4.0 base score of 4.8 classifies it as a medium severity issue, reflecting moderate impact and exploit complexity. No known exploits have been observed in the wild yet, but the exploit details have been publicly disclosed, increasing the risk of future exploitation. The vulnerability affects all Nokogiri versions from 1.18.0 through 1.18.7, making it critical for organizations using these versions to assess their exposure and apply mitigations promptly. Given Nokogiri's widespread use in Ruby-based web applications, this vulnerability could impact a broad range of software environments that rely on XML/HTML parsing, especially those processing untrusted or user-supplied data locally.

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 22 Jun 2025, 19:34 UTC

Technical details

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