Medium · published September 26, 2026
The SOAP HTTP client guards its response buffer growth with a check that relies on signed integer overflow, which is undefined behaviour and is not guaranteed to trigger. When the check is optimised away, a malicious SOAP server can make the client allocate a buffer far smaller than the data it then writes into it, producing a heap buffer overflow.
| Product | Versions | Fixed in |
|---|---|---|
| php/php | ≥ 8.2.0, < 8.2.34 | 8.2.34 |
| php/php | ≥ 8.3.0, < 8.3.35 | 8.3.35 |
| php/php | ≥ 8.4.0, < 8.4.26 | 8.4.26 |
| php/php | ≥ 8.5.0, < 8.5.11 | 8.5.11 |