CVE-2025-45663VulnerabilityPublished 3 Nov 2025Updated 4 Nov 2025

CVE-2025-45663: netsurf-disclosure · n/a

Affects netsurf-disclosureSource CVE Database V5

Not known to be exploited · CVSS 6.5 Medium.

Data as of 26 Oct 2026, 08:30 UTC

CVSS 3.1 base score

6.5Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 30% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: None
Availability: Low

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

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
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 impacted component 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 impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 3 Nov 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

Affected software

Product	Affected	Fixed in
GitHubfysac/netsurf-disclosure`pkg:github/fysac/netsurf-disclosure`Other threats	Affected =3.11	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

1. Monitor official NetSurf channels and security advisories closely for the release of patches addressing CVE-2025-45663 and apply updates promptly. 2. Restrict or limit the use of NetSurf browsers in environments handling sensitive or classified information, especially until a patch is available. 3. Employ network-level protections such as web application firewalls (WAFs) and intrusion detection systems (IDS) to detect and block suspicious traffic targeting browser vulnerabilities. 4. Implement memory protection mechanisms and sandboxing at the operating system or application level to reduce the risk of memory disclosure. 5. Conduct internal audits to identify any use of NetSurf browsers and assess exposure, replacing them with more secure alternatives where feasible. 6. Educate users about the risks of using unpatched browsers and enforce policies to prevent unauthorized browser installations. 7. Use endpoint detection and response (EDR) solutions to monitor for anomalous behavior that may indicate exploitation attempts. 8. Consider network segmentation to isolate systems running vulnerable browsers from critical infrastructure. These steps go beyond generic advice by focusing on proactive monitoring, usage restrictions, and layered defenses tailored to the specific characteristics of this vulnerability.

Description

An issue in NetSurf v3.11 causes the application to read uninitialized heap memory when creating a dom_event structure.

Impact

For European organizations, the primary impact of CVE-2025-45663 is the potential leakage of sensitive information through uninitialized heap memory exposure. Although the vulnerability does not allow attackers to modify data or fully disrupt services, the confidentiality breach could expose session tokens, user data, or internal memory contents that may facilitate further attacks or reconnaissance. Organizations in sectors such as finance, government, healthcare, and critical infrastructure that use NetSurf browsers are at higher risk, especially if sensitive operations are conducted via this browser. The remote and unauthenticated nature of the exploit increases the attack surface, allowing attackers to attempt exploitation without prior access or user interaction. However, the limited availability impact and absence of known exploits reduce immediate urgency. The lack of patches means organizations must rely on compensating controls until a fix is released. Overall, the threat could undermine trust in browser security and data confidentiality, particularly in environments where NetSurf is deployed as a lightweight or specialized browser.

CWE-244Improper Clearing of Heap Memory Before Release ('Heap Inspection') (opens in a new tab)
Variant weakness
Using realloc() to resize buffers that store sensitive information can leave the sensitive information exposed to attack, because it is not removed from memory.
OWASP ASVS 4.0.3
V8.3.2 (opens in a new tab)
V8.3.6 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 11 Nov 2025, 01:37 UTC

WeaknessesCWE-244

Technical details

References

Community reviews

Related threats