# CVE-2021-3156: Sudo Heap-Based Buffer Overflow Vulnerability

- Exploited (CISA KEV): yes, added 2022-04-06
- Published: 2021-01-26
- CVSS: 7.8 HIGH (v3.1)
- EPSS: 100.0% (100th percentile)
- CWE: CWE-122, CWE-193

Sudo before 1.9.5p2 contains an off-by-one error that can result in a heap-based buffer overflow, which allows privilege escalation to root via "sudoedit -s" and a command-line argument that ends with a single backslash character.

## Edge WAF coverage (claimed by vendors, not measured)

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | Before feed history | — | — |
| AWS | No public claim | — | — |
| Microsoft Azure | No public claim | — | — |
| Google Cloud | Before feed history | — | — |
| Fastly | Before feed history | — | — |
| F5 | Before feed history | — | — |
| Akamai | No public source | — | — |
| OWASP CRS | Before feed history | — | — |

## Social

1 posts seen since 2026-11-02.

- Exploit repository (unvetted): https://github.com/AmroYasserH/DFIR-CVE-2021-3156-Incident-Response

"No public claim" means no vendor statement names this CVE; "Before feed history" means the CVE is older than the vendor feed. In both cases generic rules may still block it.

HTML: https://cve.vigilbase.com/cve/CVE-2021-3156 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2021-3156