CVE-2026-115560 PHP Group · PHP

PHP - Remote Code Execution via Session Upload Progress and Serializer Switching

Vulnerability at a glance

Severity, exploitation likelihood & attack requirements

CVSS severity
Not scoredNo score in current feeds
EPSS · exploitation likelihood
Not available No score available
EPSS trend
UnavailableNo comparable history
Known exploitation
Not in KEV CISA KEV catalog Absence does not establish safety
Attack vector
Not reported
Attack complexity
Not reported
Privileges required
Not reported
User interaction
Not reported
Exploit availability & maturity
Not scored Availability not established No explicit exploit maturity assessment View exploit evidence
How to read the colors & trend
Higher exposureElevatedModerateLower exposureUnknown / unassessed

CVSS colors follow its reported severity. Attack-factor colors describe each requirement, not an overall risk rating. Gray also covers absence from KEV; absence does not establish safety.

EPSS display bands: below 1% blue, 1–10% amber, 10–50% orange, 50% and above red. These are presentation bands, not FIRST severity categories. The trend compares daily EPSS probabilities, not percentile ranks; “pp” means percentage points. The sparkline shows relative movement, with its vertical scale fitted to the observed scores.

Already protected by existing Atomicorp rules No new CVE-specific rule required.

Atomicorp ModSecurity protection

Protected by Atomicorp rules

Atomicorp ModSecurity rules block attacks exploiting this vulnerability. Keep your rules current.

By targeting underlying attack techniques and CWE weakness classes, existing rules can protect against newly disclosed vulnerabilities. Rule changes are regression-tested against attack and false-positive corpora.

1 rule identified View rules & research details →

WAF protection does not change the CVSS or EPSS score. Keep your software patched and your Atomicorp rules current.

CISA SSVC

No CISA SSVC assessment is available in the current source data.

On this page

Why existing Atomicorp rules protect this CVE

Existing rule 314143 protects against the session upload-progress attack vector associated with CVE-2026-115560. No new CVE-specific rule is required.

This is a manual engineering finding based on PHP’s advisory and review of the existing rule. Atomicorp has not performed a CVE-2026-115560 PoC or exploit replay for this finding. The existing protection supplies the finding; adding a CVE identifier to documentation or an alert does not create new matching logic.

What PHP disclosed

PHP’s October 23 advisory describes a potential remote code execution issue involving session upload-progress handling and session serialization. PHP recommends a configuration mitigation while preparing a fix for a regular release. As of October 24, the fixed release and full advisory were still pending.

Amazon Linux rates the issue Important, with CVSS v3.1 8.1 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H). This is Amazon’s assessment, not an NVD score. Our October 24 checks found no NVD record or FIRST EPSS score for this identifier, so those automated metrics remain unavailable.

Related research discusses CVE-2026-109618 and CVE-2026-109619 . These are separate vulnerabilities with their own vendor advisories and remediation.

CVE Details

  • Protection status: Protected by Atomicorp rules · About protection statuses
  • CVE: CVE-2026-115560
  • Name: PHP - Remote Code Execution via Session Upload Progress and Serializer Switching
  • Severity: High
  • CVSS: N/A
  • CVSS version: N/A
  • CVSS source: N/A
  • CWE: N/A
  • Vendor: PHP Group
  • Vulnerable product: PHP
  • Latest Update: 2026-10-24
  • Reviewed Rule IDs: 314143
  • Reviewed rules with current blocking actions: 314143
Technical vulnerability details · CVSS assessments, exploit evidence & CPE data

CVSS assessments

No CVSS assessment is available in the current source data. Exploitability and impact subscores describe the vulnerability’s technical characteristics. Exploit maturity describes the reported state of exploitation; these are separate measures.

Assessment source: NVD record · CVE record

Vulnerable CPE configurations

No vulnerable CPE configurations are supplied in the current NVD record. See the affected-product information and vendor guidance on this page.

  1. Maintain the reviewed Atomicorp rules. Keep your Atomicorp commercial rules current and confirm that the reviewed rules (314143 ) have not been locally disabled. Atomicorp commercial rules are enabled by default. If you use Atomic WAF, review the applicable policy and rule settings.

  2. Apply the vendor’s remediation. WAF protection is defense in depth and does not replace upgrading or following the affected vendor’s guidance. PHP recommends setting session.upload_progress.enabled=0 until its fix is released. Follow the PHP advisory and session configuration documentation to apply that mitigation and restart the relevant PHP workers.

    Keep the mitigation in place, maintain current Atomicorp rules, and install the applicable supported PHP or vendor security update when available. PHP’s October 21 releases addressed CVE-2026-109618 and CVE-2026-109619; follow the October 23 advisory for this issue’s fix. Test application functionality after maintenance.

  3. Validate after changes. Confirm rule updates are current, review WAF events for the affected application, and test application behavior after vendor upgrades, mitigations, or local policy changes.

Research Notes

Atomicorp WAF protections are designed around attack techniques and exploit behaviors, allowing existing protections to apply across multiple vulnerabilities without requiring a unique rule for every CVE.

Public Vulnerability References

Test or Research Source

  • Source: https://www.php.net/archive/2026.php#2026-10-23-1
  • Tags: manual-review
  • Research basis: Manual engineering review identifies existing Atomicorp rule 314143 as protecting the session upload-progress activation path required by CVE-2026-115560. The finding is based on PHP’s advisory, the current rule’s blocking behavior and the shared attack vector; no CVE-specific PoC or exploit replay was performed.
  • Notes: No new CVE-specific matching logic is required. Follow PHP’s mitigation guidance while awaiting the scheduled fix.

Research Note Context

This research note documents exploit-technique analysis associated with this vulnerability and references Atomicorp WAF protections observed during engineering review, testing, or validation activities.

Atomicorp security controls are generally designed to identify and mitigate attack techniques and exploit behaviors rather than individual CVE identifiers. As a result, protections developed for one vulnerability may also apply to related attack variants and future vulnerabilities using similar techniques.

Learn More

Atomicorp develops commercially supported security technologies for web applications, servers, endpoints, workloads, and legacy enterprise platforms.

Organizations interested in protecting systems against exploit techniques associated with vulnerabilities such as this one can learn more about:

  • Atomic ModSecurity Rules: commercially maintained WAF rules for ModSecurity deployments, including protections for web attacks, bots, scanners, malware, exploitation attempts, and emerging vulnerability classes.
  • Atomic WAF: an enterprise web application firewall with Atomicorp rules, centralized management, reporting, authentication controls, and operational tooling.
  • Atomic ModSecurity Integrator: a special licensing option for MSPs, MSSPs, OEMs, VARs, reverse proxy providers, and other integrators who want to incorporate Atomicorp ModSecurity rule technology into their own products or services.
  • Atomic OSSEC: an enterprise OSSEC-based intrusion detection, compliance, and security monitoring platform.
  • Atomic Protector: workload protection for Linux, web, cloud, data center, and hybrid environments.

For additional information, product evaluations, or technical discussions, visit https://www.atomicorp.com/ or https://modsecurity.io/ .