Raw vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:HSummary
CVE-2021-35211 is a critical-severity Out-of-bounds Write (CWE-787) vulnerability in Solarwinds Serv-U. Its CVSS base score is 9.0 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 0.2% 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.
CVE-2021-35211 is a remote code execution vulnerability in SolarWinds Serv-U Managed File Transfer and Serv-U Secure FTP for Windows versions prior to 15.2.3 HF2. It stems from a Remote Memory Escape issue classified under CWE-787 that permits out-of-bounds memory access, allowing an attacker to execute arbitrary code on the affected host.
An unauthenticated remote attacker can exploit the flaw over the network to obtain privileged access to the Windows system running the Serv-U service. The CVSS 3.1 score of 9.0 reflects the combination of network attack vector, high complexity, and full impact on confidentiality, integrity, and availability within a changed scope.
Microsoft and SolarWinds advisories recommend immediate upgrade to version 15.2.3 HF2 or later. The vulnerability was used as a zero-day by a threat actor and is listed in CISA’s Known Exploited Vulnerabilities catalog, confirming active in-the-wild exploitation prior to public disclosure.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2021-21854
Vulnerability Data
Microsoft discovered a remote code execution (RCE) vulnerability in the SolarWinds Serv-U product utilizing a Remote Memory Escape Vulnerability. If exploited, a threat actor may be able to gain privileged access to the machine hosting Serv-U Only. SolarWinds Serv-U Managed…
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File Transfer and Serv-U Secure FTP for Windows before 15.2.3 HF2 are affected by this vulnerability.
- CWE(s)
- KEV Date Added
- 03 November 2021
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
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.
Out-of-bounds writes that corrupt control flow or inject shellcode are rendered non-executable by the same memory protections.
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.
Secure-development practices (static analysis, bounds checking, code review) are the primary means of preventing out-of-bounds writes.
Vulnerability scanning and recording can discover out-of-bounds write flaws so they can be remediated.
Patching or replacing vulnerable software directly eliminates known instances of this coding weakness.
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.
Security testing in development and acceptance can detect and prevent out-of-bounds write defects.
Secure development life cycle mandates practices that prevent out-of-bounds writes.
Application security requirements can specify bounds-checking and safe memory handling.
Secure architecture and engineering principles reduce the likelihood of buffer overflows.
Secure coding directly addresses out-of-bounds writes through language choice and coding standards.
Change management can enforce review gates that catch unsafe memory operations before deployment.