Quick answers
- Is CVE-2026-17544 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-17544 being exploited in the wild.
- How severe is CVE-2026-17544?
- Informational severity, with a CVSS score of 8.1, published 30 July 2026.
- Which products and versions are affected?
- PHP Group PHP 8.4.* before 8.4.24, 8.5.* before 8.5.9.
- Is there a fix for CVE-2026-17544?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-17544 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-17544?
- Check whether you run PHP Group PHP at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
An out-of-bounds write vulnerability exists in the bc_str2num() function within PHP's BCMath extension (ext-bcmath). The flaw occurs when a user-provided scale truncates a number and trailing zeros are subsequently trimmed; the code fails to update the 'fractional_end' pointer after adjusting 'str_scale'. When bc_copy_and_toggle_bcd() is later called, it copies the original untruncated string into a buffer sized for the truncated version. Depending on the size of the input, this results in either stack-based or heap-based memory corruption. The issue is fixed in PHP versions 8.4.24 and 8.5.9.
Affected products
- PHP Group PHP 8.4.* before 8.4.24, 8.5.* before 8.5.9
Timeline
- 2026-07-30: advisory
- 2026-07-30: disclosed