Quick answer
Direct answer
Risk scores
| CVSS metric | What it means |
|---|---|
| Attack vector (AV:N) | Network: reachable remotely |
| Attack complexity (AC:L) | Low complexity |
| Attack requirements (AT:N) | No attack requirements |
| Privileges required (PR:N) | No privileges required |
| User interaction (UI:N) | No user interaction |
| Confidentiality (VC:H) | High confidentiality impact |
| Integrity (VI:H) | High integrity impact |
| Availability (VA:H) | High availability impact |
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:N/R:X/V:X/RE:X/U:X
About Php
CVE-2026-17544 affects Php, a product from Php. Before acting, confirm where Php runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.
What the flaw is
In plain terms: Attacker-provided inputs to bccomp() could lead to an out-of-bounds write with stack and heap corruption in PHP versions from 8.4.* before 8.4.24 and from 8.5.* before 8.5.9.
The weakness class is Out of Bounds Write. The program writes past the end of a buffer, a common path to code execution.
Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Affected versions and timeline
| Field | Detail |
|---|---|
| Product | Php |
| Affected versions | Php from 8.4.0 before 8.4.24; Php from 8.5.0 before 8.5.9 |
| Published | Jul 30, 2026 |
| Last modified | Aug 5, 2026 |
| Added to CISA KEV | Not listed |
| Assigning CNA | security@php.net |
How to detect it
- Inventory every instance of Php and record the running version against the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
- Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.
How to fix it
- Apply the fixed version of Php named in the vendor advisory.
- If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
- Rescan after the change to prove the exposure is gone, then close the ticket.
CTEM action plan
| CTEM stage | What to do for this CVE |
|---|---|
| Scope | Add every business service that depends on Php to the current CTEM cycle. |
| Discover | Find all instances, including shadow and cloud deployments, and record versions and exposure. |
| Prioritize | Rank using EPSS and CVSS together with asset exposure and business impact. |
| Validate | Confirm the flaw is reachable and exploitable in your environment and that compensating controls work. |
| Mobilize | Assign the fix to the asset owner with a due date matched to the priority, then verify closure. |
CWE References
- CWE-787: Out of Bounds Write More CVEs with this weakness
Technical References
Frequently asked questions
Related CVEs
Improper escaping of backslashes in attacker-provided parameters would allow for trivial SQL injection in PHP versions from 8.2.* before 8.2.33, from 8.3.* before 8.3.33, from 8.4.* before 8.4.24, and from 8.5.* before 8.5.9.
In PHP versions 8.2.* before 8.2.31, 8.3.* before 8.3.31, 8.4.* before 8.4.21, and 8.5.* before 8.5.6, the SOAP extension's object deduplication mechanism stores pointers to PHP objects in a global map without incrementing their reference counts. When an apache:Map node contains duplicate keys, processing the second entry overwrites the first in the temporary result map, freeing the original PHP object while its stale pointer remains in the map. A subsequent href reference to the freed node can copy the dangling pointer into the result. As PHP string allocations can reclaim the freed memory region, an attacker with control over the SOAP request body can exploit this use-after-free to achieve remote code execution.
In PHP versions 8.2.* before 8.2.31, 8.3.* before 8.3.31, 8.4.* before 8.4.21, and 8.5.* before 8.5.6, the PDO Firebird driver improperly handles NUL bytes when preparing SQL queries. During token-by-token query construction, a string token containing a NUL byte is copied via strncat(), which stops at the NUL byte, dropping the closing quote and causing subsequent SQL tokens to be interpreted as part of the string. This allows SQL injection when attacker-controlled values are quoted via PDO::quote() and embedded in SQL statements.
FrankenPHP is a modern application server for PHP. Prior to 1.11.2, FrankenPHP’s CGI path splitting logic improperly handles Unicode characters during case conversion. The logic computes the split index (for finding .php) on a lowercased copy of the request path but applies that byte index to the original path. Because strings.ToLower() in Go can increase the byte length of certain UTF-8 characters (e.g., Ⱥ expands when lowercased), the computed index may not align with the correct position in the original string. This results in an incorrect SCRIPT_NAME and SCRIPT_FILENAME, potentially causing FrankenPHP to execute a file other than the one intended by the URI. This vulnerability is fixed in 1.11.2.
FrankenPHP is a modern application server for PHP. Prior to 1.11.2, when running FrankenPHP in worker mode, the $_SESSION superglobal is not correctly reset between requests. This allows a subsequent request processed by the same worker to access the $_SESSION data of the previous request (potentially belonging to a different user) before session_start() is called. This vulnerability is fixed in 1.11.2.
Out-of-bounds Write, Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') vulnerability in azerothcore azerothcore-wotlk (deps/zlib modules). This vulnerability is associated with program files inflate.C. This issue affects azerothcore-wotlk: through v4.0.0.
Earn your free CTEM certification.
Learn to scope, prioritize, validate and mobilize fixes for CVEs like CVE-2026-17544 with a free CTEM certification.
Beginner / Practitioner / Program Leader
Explore certifications