What's the vulnerability?
The convert.base64-encode, convert.quoted-printable-encode and convert.quoted-printable-decode stream filters accept a line-break-chars option whose length is tracked separately from the string itself. The filter constructors duplicate the value with pestrdup(), which stops at the first NUL byte, while keeping the original length. When the filter later emits a line break it copies the recorded length out of the truncated allocation, reading past its end and placing adjacent heap bytes into the filter output.
Business impact & how R4IM helps
This advisory is on our active-exploitation watchlist. Attackers are using it for initial access, privilege escalation or lateral movement in real-world intrusions. R4IM's offensive security and SOC teams already have detections, exploit replicas and remediation playbooks for this issue.
Targeted vulnerability assessment to confirm which of your assets are actually exploitable — not just theoretically affected.
Our pentesters chain this CVE into realistic attack paths so you see business impact, not just a scan finding.
If the affected product is internet-facing, our AppSec team will harden it against this and related OWASP-class issues.
Continuous monitoring with custom detections for this CVE deployed across your endpoints, identity and cloud.
Recommended remediation
- Inventory all assets running the affected vendor and product, including shadow IT and third-party hosted instances.
- Apply the vendor patch or mitigation referenced in the advisories below. Where no patch exists, isolate the asset or restrict network exposure.
- Hunt for indicators of prior compromise — exploitation of this class of bug often predates public disclosure.
- Deploy detections for the exploit primitives (network signature, EDR rule, WAF rule) and re-test after remediation.
Need help executing these steps? Our team typically completes validation and remediation within a single patch cycle. Request remediation support →
Vendor & research references
- https://github.com/php/php-src/security/advisories/GHSA-88hq-2827-7pg6 · security@php.net