VULNpocalypse

CVE-2026-109618: PHP Memory Corruption Vulnerability

Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.

Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.

What it is

PHP uses longjmp() for out-of-memory (OOM) errors to exit the current context and abort handling of the request. Some contexts may not properly account for this scenario and leave request memory in an uninitialized state before performing an allocation. The subsequent request cleanup procedure may read or branch on this memory. Multiple OOM strategies can consistently trigger this condition and lead to remote code execution (RCE).

Description quoted from the CVE record (assigned by php, published 2026-10-21).

Weakness: CWE-416 Use after free; CWE-755 Improper Handling of Exceptional Conditions; CWE-824 Access of uninitialized pointer; CWE-1325 Improperly controlled sequential memory allocation; CWE-1419 Incorrect Initialization of Resource

How it can be exploited

Exploitable over the network with high attack complexity only when specific conditions are present needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: no. Technical impact: total.

On CISA KEV since
2026-10-26
US federal deadline
2026-10-29
Ransomware use
Not known

Public exploit evidence (Exploit Observer)

Also known as: BDU:2026-17191, EDB-52704, SNYK-ALMALINUX8-PHP-21689249, SNYK-ALMALINUX8-PHP-21689255, SNYK-ALMALINUX8-PHP-21689365, SNYK-ALMALINUX9-PHP-21691187, SNYK-ALMALINUX9-PHP-21691204, SNYK-ORACLE10-PHP84GD-21432906, SNYK-ORACLE10-PHP84OPCACHE-21432969, SNYK-ORACLE10-PHPFPM-21432972, SNYK-ORACLE10-PHPGMP-21433046, SNYK-ORACLE10-PHPLDAP-21433031, SNYK-ORACLE10-PHPOPCACHE-21432907, SNYK-ORACLE10-PHPXML-21433012, SNYK-SLES156-PHP7MYSQL-21464651, SNYK-SLES157-PHP7FPM-21464954, SNYK-SLES157-PHP7PHAR-21464752, SNYK-UBUNTU2604-PHP85-21373920

VEDAS cluster: VEDAS:BARGEBAUBLE

Exploit Observer links 167 pieces of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (167)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

Research and write-ups (42)

Vulnerability databases and vendor advisories (32)

Catalogue entries, not exploit evidence.

News (1)

2113 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS
1.000
very likely to be attacked soon
VEDAS
0.980
strong exploit evidence
On CISA KEV
Yes, since 2026-10-26
Detection rule
Nuclei · Suricata
EPSS (chance of attack)
100.1Added to CISA KEV 2026-10-26CVE-2026-109618 EPSS over time2026-102026-11-01
VEDAS (exploit evidence)
100.9Added to CISA KEV 2026-10-26CVE-2026-109618 VEDAS over time2026-102026-11-01

Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish. The vertical line is the day CISA added it to its exploited list.

VEDAS flagged this bug about 2 days before CISA confirmed attacks.

Who is affected

ProductAffectedNot affected
PHP Group PHP (php-src)from 8.2.* before 8.2.35
from 8.3.* before 8.3.36
from 8.4.* before 8.4.27
from 8.5.* before 8.5.12		Not stated

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

Exploit Observer also maps it to: php php, php_group php, ооо_«а-реал_консалтинг» программный_межсетевой_экран_интернет_контроль_сервер.

How to fix it

Fixed versions stated in the CVE record: 8.2.35, 8.3.36, 8.4.27, 8.5.12.

CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset’s internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

Vendor guidance:

How to detect it

Nuclei template (active check)

PHP - session.upload_progress Session Fixation (rfc1867)

The rfc1867 session.upload_progress handler reads the session identifier supplied in a multipart/form-data request body and initializes the upload-progress session with it even when cookies are the only configured session transport, letting an unauthenticated attacker fix the session identifier used by the handler. When chained with a local file inclusion primitive (and upload-progress cleanup disabled) the attacker-controlled session file can be included to execute code; the same reachable code path is abused by the CVE-2026-109619 use-after-free, including its self-leaking ASLR-bypass variant that reflects heap memory back through the Set-Cookie PHPSESSID value. This non-destructive probe sends two benign upload-progress multipart requests and flags either of two preconditions the exploit chains require: (1) a session identifier with illegal characters produces the handler’s session-ID validation warning (display_errors path), or (2) an attacker-chosen session identifier supplied in the request is reflected back in Set-Cookie (session.use_strict_mode=0 fixation, the primitive the heap-leak stages read). It does not confirm code execution.

Name and description quoted from the template, written by VEDAS.

The template sends 2 requests (POST /, POST /?PHPSESSID={{marker}}); it decides using dsl matchers. Severity in the template: high. Marked as not yet verified against a live vulnerable target.

Run it against a host you own or are authorised to test:

bash
nuclei -u https://your-host -t CVE-2026-109618.yaml
Show the template (90 lines)
yaml
id: CVE-2026-109618

info:
  name: "PHP - session.upload_progress Session Fixation (rfc1867)"
  author: vedas-arpsyndicate
  severity: high
  description: |
    The rfc1867 session.upload_progress handler reads the session identifier supplied in a multipart/form-data
    request body and initializes the upload-progress session with it even when cookies are the only configured
    session transport, letting an unauthenticated attacker fix the session identifier used by the handler. When
    chained with a local file inclusion primitive (and upload-progress cleanup disabled) the attacker-controlled
    session file can be included to execute code; the same reachable code path is abused by the CVE-2026-109619
    use-after-free, including its self-leaking ASLR-bypass variant that reflects heap memory back through the
    Set-Cookie PHPSESSID value. This non-destructive probe sends two benign upload-progress multipart requests
    and flags either of two preconditions the exploit chains require: (1) a session identifier with illegal
    characters produces the handler's session-ID validation warning (display_errors path), or (2) an
    attacker-chosen session identifier supplied in the request is reflected back in Set-Cookie
    (session.use_strict_mode=0 fixation, the primitive the heap-leak stages read). It does not confirm code
    execution.
  reference:
    - https://www.exploit.observer/?keyword=CVE-2026-109618&match=exact
    - https://subdomain.center/?engine=ammonites&keyword=php&match=exact
  classification:
    cvss-metrics: 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
    cvss-score: 9.2
    cve-id: CVE-2026-109618
    cwe-id: CWE-384
  metadata:
    verified: false
    max-request: 2
  tags: cve,cve2026,php,session-fixation,upload-progress,intrusive

variables:
  marker: "{{rand_base(12)}}"
  sid_invalid: "{{randstr}}/{{rand_base(20)}}"

http:
  - raw:
      - |
        POST / HTTP/1.1
        Host: {{Hostname}}
        Content-Type: multipart/form-data; boundary=----{{randstr}}

        ------{{randstr}}
        Content-Disposition: form-data; name="PHPSESSID"

        {{sid_invalid}}
        ------{{randstr}}
        Content-Disposition: form-data; name="PHP_SESSION_UPLOAD_PROGRESS"

        {{marker}}
        ------{{randstr}}
        Content-Disposition: form-data; name="f"; filename="{{marker}}.txt"
        Content-Type: text/plain

        Z
        ------{{randstr}}--
      - |
        POST /?PHPSESSID={{marker}} HTTP/1.1
        Host: {{Hostname}}
        Content-Type: multipart/form-data; boundary=----{{randstr}}

        ------{{randstr}}
        Content-Disposition: form-data; name="PHPSESSID"

        {{marker}}
        ------{{randstr}}
        Content-Disposition: form-data; name="PHP_SESSION_UPLOAD_PROGRESS"

        {{marker}}
        ------{{randstr}}
        Content-Disposition: form-data; name="f"; filename="{{marker}}.txt"
        Content-Type: text/plain

        Z
        ------{{randstr}}--

    disable-cookie: true
    stop-at-first-match: true

    matchers-condition: or
    matchers:
      - type: dsl
        name: session-id-validation-warning
        dsl:
          - 'contains(body, "Session ID is too long or contains illegal characters")'
      - type: dsl
        name: attacker-session-id-reflected
        dsl:
          - 'contains(all_headers, "PHPSESSID={{marker}}")'

CVE-2026-109618.yaml on GitHub

Suricata rules (network detection)

1 rule that alert on traffic matching this exploit: VEDAS CVE-2026-109618 PHP - session.upload_progress Session Fixation (rfc1867) Attempt. Add them to your Suricata rule set and reload.

Show the rules
suricata
alert http $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS (msg:"VEDAS CVE-2026-109618 PHP - session.upload_progress Session Fixation (rfc1867) Attempt"; flow:established,to_server; http.method; content:"POST"; http.request_body; content:"PHP_SESSION_UPLOAD_PROGRESS"; nocase; fast_pattern; content:"PHPSESSID"; nocase; classtype:attempted-admin; reference:cve,CVE-2026-109618; reference:url,https://www.exploit.observer/?keyword=CVE-2026-109618&match=exact; reference:url,https://subdomain.center/?engine=ammonites&keyword=php&match=exact; sid:1043400; rev:3;)

CVE-2026-109618.rules on GitHub

Advisories on this CVE

References

Vendor advisories and patches

Exploits and technical analysis

Government sources

Other references

Other databases

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer, vedas-signatures. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.