Is CVE-2026-34084 actively exploited?

No active exploitation of CVE-2026-34084 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-34084 be exploited remotely?

Yes. CVE-2026-34084 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-34084?

CVE-2026-34084 has a CVSS score of 9.8 (CRITICAL).

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CRITICAL

CVE-2026-34084

CWE-502Published: May 5, 2026· Updated: May 8, 2026

9.8

CVSS v3.1

EPSS:0.10%probability of exploitation in 30 daysPercentile:27.2th

Official Description

PhpSpreadsheet is a library for reading and writing spreadsheet files. In versions 1.30.2 and earlier, 2.0.0 through 2.1.14, 2.2.0 through 2.4.3, 3.3.0 through 3.10.3, and 4.0.0 through 5.5.0, when the filename argument to IOFactory::load() is user-controlled, an attacker can supply a PHP stream wrapper path (such as phar://, ftp://, or ssh2.sftp://) that passes the is_file() check in File::assertFile(). The phar:// wrapper triggers deserialization of the PHAR metadata, which can lead to remote code execution if a suitable gadget chain is available in the application. The ftp:// and ssh2.sftp:// wrappers can be used for server-side request forgery. This issue has been fixed in versions 1.30.3, 2.1.15, 2.4.4, 3.10.4, and 5.6.0.

NVD Source

Technical Analysis

CVE-2026-34084 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

From a weakness classification perspective (CWE-502): Insecure deserialization vulnerabilities allow attackers to inject malicious objects during deserialization, potentially enabling remote code execution.