# CVE-2025-54574: Squid's URN Handling can lead to Buffer Overflow

- Exploited (CISA KEV): no
- Published: 2025-08-01
- CVSS: 9.3 CRITICAL (v3.1)
- EPSS: 22.1% (98th percentile)
- CWE: CWE-122

Squid is a caching proxy for the Web. In versions 6.3 and below, Squid is vulnerable to a heap buffer overflow and possible remote code execution attack when processing URN due to incorrect buffer management. This has been fixed in version 6.4. To work around this issue, disable URN access permissions.

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

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | Blocks by default | 2025-08-07 | 6 |
| AWS | No public claim | — | — |
| Microsoft Azure | No public claim | — | — |
| Google Cloud | No public claim | — | — |
| Fastly | Before feed history | — | — |
| F5 | No public claim | — | — |
| Akamai | No public source | — | — |
| OWASP CRS | No public claim | — | — |

### Cloudflare

- 2025-08-07 · new · rule e76e65f5a3aa43f49e0684a6baec057a · default Block
  > Squid - Buffer Overflow - CVE:CVE-2025-54574. Previous action: N/A. New action: Block. This is a New Detection
  Source: https://developers.cloudflare.com/changelog/post/2025-08-07-emergency-waf-release/

"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-2025-54574 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2025-54574