Unauthenticated RCE in SPIP Saisies plugin via _anciennes_valeurs PHP code injection
CVE-2025-71243 is a critical unauthenticated remote code execution vulnerability in the SPIP plugin 'Saisies pour formulaire' (Saisies) affecting versions 5.4.0 through 5.11.0. The flaw is caused by unsafe handling of the user-controlled _anciennes_valeurs form parameter in the plugin’s form-loading path. According to the provided content, saisies_formulaire_charger_generer_hidden_ancienne_valeur_depubliee() can assign attacker-supplied _anciennes_valeurs directly to $encode without sanitization, and the value is then appended into $flux['data']['_hidden'] via the formulaire_charger pipeline. In SPIP, underscore-prefixed fields bypass protege_champ() escaping, and the #ACTION_FORMULAIRE balise renders _hidden content with interdire_scripts=false, disabling normal script filtering. Because SPIP templates are compiled into PHP and executed via eval(), injected <?php ... ?> sequences can survive rendering and execute server-side. The issue is reachable during the form 'charger' phase, so exploitation does not require successful form submission. The content states exploitation is possible with a simple unauthenticated GET or POST request containing _anciennes_valeurs, provided a publicly accessible form using the Saisies plugin is present.
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Impact, mitigation & remediation
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Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
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system, exec, passthru, shell_exec, and proc_open to reduce post-exploitation impact, though this does not remove the underlying vulnerability.Remediation
Patch, then assume compromise.
_anciennes_valeurs and instead forces server-side recomputation of the value, eliminating the attacker-controlled code injection path. Confirm that all affected instances running versions 5.4.0 through 5.11.0 are updated.Exploits
1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.
Repository purpose: provides an unauthenticated RCE exploit (CVE-2025-71243) for the SPIP ‘Saisies’ plugin, plus a Docker-based lab to reproduce the issue. Key vulnerability mechanics (as described and implemented): the Saisies pipeline function that generates a hidden field trusts the POST parameter `_anciennes_valeurs` and interpolates it into a single-quoted HTML attribute without escaping. SPIP’s `#ACTION_FORMULAIRE` rendering sets `interdire_scripts=false` for the `_hidden` field, and the template is evaluated, allowing injected `<?php ... ?>` to execute. This yields unauthenticated PHP code execution on any public page containing a saisies-powered form. Exploit capabilities (exploit.py): - Version fingerprinting: requests `/<origin>/spip.php` and parses the `Composed-By` header for `saisies(x.y.z)`; optionally fetches `/<origin>/local/config.txt` (or a config.txt URL embedded in the header) to extract the plugin version. - Optional site discovery: `--crawl` starts from `/<origin>/spip.php?page=plan` (SPIP plan/sitemap) and follows internal links (filters common static assets) until it finds a page whose HTML contains the parameter name `_anciennes_valeurs`, indicating a saisies form. - Vulnerability check: POSTs `_anciennes_valeurs` with an injected PHP `echo` marker and checks for marker presence in the response. - RCE: base64-encodes an operator-supplied command and injects PHP `system(base64_decode(...))`; extracts command output from between two known HTML markers in the response. - Interactive mode: provides a simple read-eval loop that repeatedly sends commands and prints extracted output. Repository structure: - README.md: detailed write-up, affected versions (5.4.0–5.11.0, fixed 5.11.1), exploitation example, and usage instructions. - exploit.py: standalone Python3 exploit using `requests` and basic HTML parsing. - lab/docker-compose.yml: spins up `spip:4.3-apache` plus `mariadb:10`, exposing SPIP on port 8888. - lab/setup.sh: provisions a vulnerable environment by downloading Saisies v5.11.0, activating it via DB meta update, and creating a public contact form/page that uses saisies so the exploit can be tested end-to-end.
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Recent activity
16 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A remote code execution vulnerability in the SPIP Saisies plugin, referenced as a Metasploit module PR.
A vulnerability identified as CVE-2025-71243 affecting SPIP, discussed in the context of improving a detection template to reduce false positives by verifying code execution evidence.
A previously disclosed SPIP Saisies plugin RCE used here as a reference point: template injection leading to PHP code execution when attacker-controlled input reaches rendering paths with interdire_scripts=false (e.g., _hidden).
A critical remote code execution vulnerability in the SPIP 'Saisies pour formulaire' (Saisies) plugin affecting versions 5.4.0 through 5.11.0, allowing unauthenticated remote attackers to execute arbitrary code on the server.
The version that knows your environment.
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Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
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Cross-references every affected SKU, including bundled OEM variants.
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