PHP is a widely deployed runtime; a memory-corruption bug can enable RCE or service disruption across many web apps and hosting environments.
CVE-2026-17544
Memory corruption in PHP bccomp() enabling possible code execution
Is CVE-2026-17544 being exploited?
Not confirmed. CVE-2026-17544 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.43% probability of exploitation in the next 30 days.
How severe is CVE-2026-17544?
CVE-2026-17544 is rated High with a CVSS score of 8.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-17544?
Yes. A fix has been recorded for CVE-2026-17544. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-17544 affect?
CVE-2026-17544 affects PHP 8.4 versions before 8.4.24, PHP 8.5 versions before 8.5.9, Apps using PHP BCMath extension. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-17544?
Upgrade to PHP 8.4.24 or 8.5.9+; disable BCMath if unused
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Attacker-supplied bccomp() input can cause heap/stack corruption, enabling crashes or potential remote code execution.
Patch when possible
- affected>= 8.4.* and < 8.4.24
- affected>= 8.5.* and < 8.5.9
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.