CVE-2025-1866
CVE-2025-1866 is a critical-severity vulnerability with a CVSS 4.0 base score of 10.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-119.
Key facts
- Severity: Critical (CVSS 4.0 base score 10.0)
- EPSS exploit prediction: 0% (36th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2025-5807
- Weakness: CWE-119
- Published:
- Last modified:
Description
Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerability in warmcat libwebsockets allows Pointer Manipulation, potentially leading to out-of-bounds memory access. This issue affects libwebsockets before 4.3.4 and is present in code built specifically for the Win32 platform. By default, the affected code is not executed unless one of the following conditions is met: LWS_WITHOUT_EXTENSIONS (default ON) is manually set to OFF in CMake. LWS_WITH_HTTP_STREAM_COMPRESSION (default OFF) is manually set to ON in CMake. Despite these conditions, when triggered in affected configurations, this vulnerability may allow attackers to manipulate pointers, potentially leading to memory corruption or unexpected behavior.
Frequently asked questions
- What is CVE-2025-1866?
- Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerability in warmcat libwebsockets allows Pointer Manipulation, potentially leading to out-of-bounds memory access. This issue affects libwebsockets before 4.3.4 and is present in code built specifically for the Win32 platform. By default, the affected code is not executed unless one of the following conditions is met: LWS_WITHOUT_EXTENSIONS (default ON) is manually set to OFF in CMake. LWS_WITH_HTTP_STREAM_COMPRESSION (default OFF) is manually set to ON in CMake. Despite these conditions, when triggered in affected configurations, this vulnerability may allow attackers to manipulate pointers, potentially leading to memory corruption or unexpected behavior.
- How severe is CVE-2025-1866?
- CVE-2025-1866 has a CVSS 4.0 base score of 10.0, rated critical severity.
- Is CVE-2025-1866 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (36th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2025-1866?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- Does CVE-2025-1866 have an EU (EUVD) identifier?
- Yes. CVE-2025-1866 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-5807.
- When was CVE-2025-1866 published?
- CVE-2025-1866 was published on 2025-03-03 and last updated on 2026-06-17.
References
Other CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) vulnerabilities
- CVE-2026-105285 — Critical (CVSS 10.0): A security vulnerability has been detected in Totolink A3002MU 1.0.0-B20230403.1455. This affects an unknown function…
- CVE-2026-104610 — Critical (CVSS 10.0): A security vulnerability has been detected in Tenda HG7, HG9 and HG10 300001138_en_xpon. This impacts the function…
- CVE-2026-101039 — Critical (CVSS 10.0): A vulnerability was identified in FAST FAC1900R 20190827_2.0.2. Affected by this issue is the function copy_msg_element…
- CVE-2026-96257 — Critical (CVSS 10.0): A flaw has been found in Fast FAC1203R Gigabit Edition 2.0.4. Affected by this issue is the function copy_msg_element…
- CVE-2026-94089 — Critical (CVSS 10.0): A vulnerability was determined in D-Link DIR-868L 2.01b05. This issue affects the function strcpy of the file…
- CVE-2026-94003 — Critical (CVSS 10.0): A vulnerability has been found in Comfast CF-N1-S 2.6.0.1. Impacted is the function get_css_path_from_uri of the file…