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Vulnerability record · CVE-2026-71981 · published 1 September 2026

CVE-2026-71981: Deserialization of untrusted data vulnerability

Cypht before 2.12.2 contains a PHP object injection vulnerability that allows authenticated attackers to execute arbitrary operating system commands by supplying a crafted PHP object graph in the back_query GET parameter of the logout handler. Attackers can pass a base64-encoded serialized payload through this parameter, which is decoded and passed directly to unserialize() without an allow-list, signature check, or type restriction, enabling gadget-chain exploitation to achieve remote code execution as the web server process.

8.7 CVSS 4.0 High EPSS 0.97% · top 39.5% CWE-502 · Deserialization of untrusted data Deferred
8.7CVSS 4.0 base score
0.97%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
4References
8 Sep 2026Last modified by NVD

Description

Cypht before 2.12.2 contains a PHP object injection vulnerability that allows authenticated attackers to execute arbitrary operating system commands by supplying a crafted PHP object graph in the back_query GET parameter of the logout handler. Attackers can pass a base64-encoded serialized payload through this parameter, which is decoded and passed directly to unserialize() without an allow-list, signature check, or type restriction, enabling gadget-chain exploitation to achieve remote code execution as the web server process.

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/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:X/R:

References

LinkTags
https://github.com/cypht-org/cypht/commit/e4aa2f34e33f9328e8c93514cc3966fc3d99925e
https://github.com/cypht-org/cypht/pull/2073
https://github.com/cypht-org/cypht/releases/tag/v2.12.2
https://www.vulncheck.com/advisories/cypht-php-object-injection-rce-via-back-query-parameter

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Source: NIST National Vulnerability Database (record CVE-2026-71981), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.