Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2020-5135 is a critical-severity Classic Buffer Overflow (CWE-120) vulnerability in Sonicwall Sonicos. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique NTDS (T1003.003); ranked in the top 2% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
A buffer overflow vulnerability tracked as CVE-2020-5135 exists in SonicOS, the operating system used by SonicWall firewalls. The flaw, categorized under CWE-120, affects SonicOS Gen 6 versions 6.5.4.7, 6.5.1.12, and 6.0.5.3, SonicOSv 6.5.4.v, and Gen 7 version 7.0.0.0. It carries a CVSS 3.1 base score of 9.8, reflecting network-accessible attack conditions with no required authentication or user interaction.
A remote attacker can exploit the issue by sending a crafted request directly to the firewall, resulting in a denial of service and potential arbitrary code execution on the affected device.
The vulnerability is documented in SonicWall PSIRT advisory SNWLID-2020-0010 and appears in the CISA Known Exploited Vulnerabilities catalog, confirming observed in-the-wild exploitation activity against unpatched systems.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2020-26382
Vulnerability Data
A buffer overflow vulnerability in SonicOS allows a remote attacker to cause Denial of Service (DoS) and potentially execute arbitrary code by sending a malicious request to the firewall. This vulnerability affected SonicOS Gen 6 version 6.5.4.7, 6.5.1.12, 6.0.5.3, SonicOSv…
more
6.5.4.v and Gen 7 version 7.0.0.0.
- CWE(s)
- KEV Date Added
- 15 March 2022
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V5.2.1
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Platform-independent managed code eliminates the need for unchecked native buffer copies that are the root cause of classic buffer overflows.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Vulnerability identification processes such as code review or scanning detect classic buffer overflows before exploitation.
Routine patching replaces vulnerable code containing unchecked buffer copies with corrected versions.
Secure development practices directly enforce bounds checking and input validation that prevent classic buffer overflows.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.