One LaTeX Snippet to RCE: CVE-2026-33046 in Indico

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One LaTeX Snippet to RCE: CVE-2026-33046 in Indico

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How to Defend: Patch, Isolate, and Detect 🛡️

Here is a concrete remediation and detection posture you should adopt immediately:

Immediate Remediation Steps

Patch to Indico 3.3.12 immediately. This is the only complete fix. All other mitigations are temporary risk reduction measures.
Disable LaTeX if you don’t critically need it. Comment out or nullify XELATEX_PATH in indico.conf, then restart both indico-uwsgi and indico-celery. No XeLaTeX path = no attack surface for this CVE.
Enable the containerized LaTeX renderer via Podman as recommended upstream. Container isolation ensures that even a successful LaTeX escape cannot reach the host filesystem or process space.
Audit filesystem permissions on the Indico service account. It should have the minimum permissions necessary — no read access to /etc/shadow, credential stores, or adjacent service configs.

Wazuh Detection: Catch the Exploitation Attempt

Even if you’ve patched, you want to know whether someone already tried to exploit this — or whether a missed instance in a shadow-IT deployment is being probed. The forensic signal to chase is XeLaTeX spawning child processes or accessing sensitive filesystem paths that a legitimate render job would never touch.

Add the following custom Wazuh rule to your local_rules.xml to alert on suspicious XeLaTeX child process spawning and sensitive file access patterns consistent with CVE-2026-33046 exploitation:

<!-- CVE-2026-33046 Indico LaTeX RCE / LFR Detection Rules -->

<group name="indico,latex,rce,lfi,cve-2026-33046">

  <!-- Rule 1: XeLaTeX spawning a shell (shell-escape abuse) -->
  <rule id="100500" level="15">
    <if_group>syscheck</if_group>
    <field name="audit.command">xelatex|pdflatex|luatex</field>
    <field name="audit.exe">sh|bash|dash|python|python3|perl|ruby</field>
    <description>CVE-2026-33046: TeX engine spawned a shell — possible LaTeX RCE via Indico</description>
    <mitre>
      <id>T1059</id>
      <id>T1190</id>
    </mitre>
  </rule>

  <!-- Rule 2: XeLaTeX reading sensitive system files (LFR indicator) -->
  <rule id="100501" level="13">
    <if_group>syscheck</if_group>
    <field name="audit.command">xelatex|pdflatex|luatex</field>
    <field name="audit.file.name">/etc/passwd|/etc/shadow|indico\.conf|\.env|id_rsa</field>
    <description>CVE-2026-33046: TeX engine accessed sensitive file — possible LFR via Indico LaTeX renderer</description>
    <mitre>
      <id>T1083</id>
      <id>T1552.001</id>
    </mitre>
  </rule>

  <!-- Rule 3: Indico celery worker spawning unexpected child processes -->
  <rule id="100502" level="12">
    <if_group>syscheck</if_group>
    <field name="audit.ppid_name">celery</field>
    <field name="audit.exe">xelatex|pdflatex</field>
    <field name="audit.syscall">execve</field>
    <description>CVE-2026-33046: Indico Celery worker invoked TeX engine — verify this is expected rendering activity</description>
    <mitre>
      <id>T1190</id>
    </mitre>
  </rule>

</group>

To make Rule 100500 and 100501 effective, ensure your Wazuh agents have Linux Audit daemon (auditd) integration enabled and that you have audit rules watching the relevant syscalls (execve, open, openat) for the Indico service account. Here’s the corresponding auditd rule snippet to drop into /etc/audit/rules.d/indico.rules:

# Track TeX engine execution by the Indico service user
# Replace 'indico' with your actual service account name
-a always,exit -F arch=b64 -F uid=indico -S execve -k indico_exec

# Track sensitive file reads originating from the Indico service account
-a always,exit -F arch=b64 -F uid=indico -S open -S openat \
  -F path=/etc/passwd -k indico_lfi
-a always,exit -F arch=b64 -F uid=indico -S open -S openat \
  -F path=/etc/shadow -k indico_lfi
-a always,exit -F arch=b64 -F uid=indico -S open -S openat \
  -F dir=/opt/indico -F filename=indico.conf -k indico_config_read

# Load rules without reboot
# augenrules --load

These rules feed directly into Wazuh’s audit decoder pipeline. Once in place, any exploitation attempt — even against an already-patched instance someone forgot on a test server — will generate a Level 12-15 alert that your SOC can action immediately.

What to Do Right Now

🔍 Inventory all Indico instances in your environment, including test servers, internal workshop tools, and departmental deployments. Shadow-IT conference tools are common in research organizations.
⬆️ Upgrade to Indico 3.3.12 immediately. If you cannot patch today, disable XELATEX_PATH as an emergency workaround and restart the affected services.
🐳 Enable containerized LaTeX rendering via Podman post-upgrade. Container isolation is the correct long-term architectural defense for any server-side document rendering pipeline — not just for this CVE.
🔐 Audit the Indico service account’s filesystem permissions. Apply least-privilege: it should not be able to read credential files, private keys, or configs belonging to adjacent services.
📊 Deploy the Wazuh auditd rules above and validate alerting with a benign test. Confirm your SIEM ingests the indico_exec and indico_lfi audit keys.
🔎 Review historical Indico logs for anomalous PDF rendering jobs — unusually long render times, rendering errors from unexpected users, or abstract submissions containing unusual character sequences could indicate prior exploitation attempts.

The broader lesson here applies well beyond Indico: any feature that passes user-controlled content into a powerful local execution engine is a high-risk attack surface, regardless of how “niche” the syntax is. We’ve seen this pattern with Markdown renderers enabling path traversal, YAML parsers enabling deserialization, and now TeX engines enabling filesystem access. If it runs on your server and accepts user input, it deserves threat modelling — even if it’s “just for formatting abstracts.” For more context on how seemingly innocuous document and API features expand your attack surface, check out our analysis of command injection via Blinko’s test button and how headless APIs and AI agents are reshaping enterprise risk.

Original source: https://nvd.nist.gov/vuln/detail/CVE-2026-33046

📚 Related Posts

A single, carefully-crafted LaTeX snippet — the kind routinely submitted to academic conference management platforms — is enough to read arbitrary files or execute code on the server hosting your Indico deployment. ⚠️ CVE-2026-33046 carries a CVSS score of 8.8 (HIGH), meaning an authenticated attacker with the ability to submit LaTeX content needs no special privileges beyond a standard conference registration. If your organization runs Indico for scientific workshops, internal events, or academic scheduling and you have XELATEX_PATH configured, you are directly in the blast radius — right now.

What Is CVE-2026-33046?

Indico is the open-source event management system originally developed at CERN and now widely used by research institutions, universities, and enterprises worldwide for managing conferences, meetings, and seminars. It integrates Flask-Multipass for flexible authentication and optionally supports server-side LaTeX rendering — allowing users to embed formatted mathematical or scientific content in abstracts, proceedings, and badges.

The vulnerability lives at the intersection of two problems: the inherent power of the LaTeX/TeX toolchain and the limits of Indico’s sanitizer. LaTeX, by design, is a Turing-complete document language with deep filesystem and shell integration primitives. Indico implements a sanitizer to block dangerous commands, but obscure TeXLive syntax — edge cases in macro expansion, category code manipulation, and less-documented TeX primitives — can be weaponized to slip past that filter entirely. The result is that an attacker doesn’t need to compromise a dependency or exploit a memory corruption bug; they simply need to know enough TeX to confuse the sanitizer.

This is classified as a server-side template/rendering injection in the LaTeX engine, not the web layer. That distinction matters because most WAFs and input validation logic are tuned for HTML/JavaScript injection patterns, not TeX command sequences. Your existing perimeter controls will likely miss it entirely.

How the Attack Works 🔧

Let’s be precise about the attack chain so you can reason about your own exposure:

Step 1 — Identify a LaTeX input field: Indico exposes LaTeX rendering in abstract submissions, contribution descriptions, and certain badge/certificate templates. Any field that passes content through XeLaTeX is a potential entry point.
Step 2 — Craft a sanitizer bypass: Using obscure TeX primitives (think \catcode manipulation, \input aliasing, or \openin/\read file handles), the attacker constructs a payload that passes Indico’s sanitizer logic but remains executable by the underlying XeLaTeX binary.
Step 3 — Trigger rendering: Submitting the payload causes the Indico server to invoke XeLaTeX. The crafted snippet then reads /etc/passwd, application secrets, or database credentials — or drops into an OS command via shell-escape primitives if that TeX flag is enabled.
Step 4 — Exfiltrate output: Results can be embedded in the rendered PDF output returned to the attacker, or side-channeled through DNS/HTTP callbacks depending on network egress controls.

In enterprise deployments I’ve reviewed, Indico instances running on internal research networks frequently run with broad filesystem permissions and without outbound egress filtering — because “it’s just a conference tool.” That operational assumption is exactly what makes this class of vulnerability so dangerous in practice.

Who Is Affected and What’s the Real Risk?

The vulnerability affects all Indico versions prior to 3.3.12 where XELATEX_PATH is set in indico.conf. If LaTeX rendering is not enabled, this specific CVE does not apply — but that configuration is common in scientific and academic deployments where beautifully formatted PDFs are a core feature expectation.

The CVSS 8.8 score reflects a scenario where an authenticated user performs the attack — but consider what “authenticated” means in Indico’s model: most conference systems allow open registration, meaning any person who creates a free attendee account can potentially reach vulnerable input fields. The effective authentication barrier may be trivially low. This is consistent with patterns we’ve seen in similar tools — as discussed when we broke down privilege escalation in Blinko and MantisBT’s SOAP API bypass, the real-world authentication bar is often far lower than the CVE description implies.

Beyond direct compromise, the secondary risk is credential harvesting. If Indico shares a server with other services — or its configuration files contain database passwords, LDAP bind credentials, or API keys — a successful local file read cascades into a much wider breach.

MITRE ATT&CK Mapping

T1059 — Command and Scripting Interpreter: LaTeX/TeX engine used as an execution environment for attacker-controlled commands.
T1083 — File and Directory Discovery: Reading local filesystem paths via TeX \input or \openin directives.
T1552.001 — Unsecured Credentials: Credentials In Files: Targeting config files (indico.conf, .env) for secrets extraction.
T1190 — Exploit Public-Facing Application: Indico is typically exposed on internal or public networks as a web application.

How to Defend: Patch, Isolate, and Detect 🛡️

Here is a concrete remediation and detection posture you should adopt immediately:

Immediate Remediation Steps

Patch to Indico 3.3.12 immediately. This is the only complete fix. All other mitigations are temporary risk reduction measures.
Disable LaTeX if you don’t critically need it. Comment out or nullify XELATEX_PATH in indico.conf, then restart both indico-uwsgi and indico-celery. No XeLaTeX path = no attack surface for this CVE.
Enable the containerized LaTeX renderer via Podman as recommended upstream. Container isolation ensures that even a successful LaTeX escape cannot reach the host filesystem or process space.
Audit filesystem permissions on the Indico service account. It should have the minimum permissions necessary — no read access to /etc/shadow, credential stores, or adjacent service configs.

Wazuh Detection: Catch the Exploitation Attempt

Even if you’ve patched, you want to know whether someone already tried to exploit this — or whether a missed instance in a shadow-IT deployment is being probed. The forensic signal to chase is XeLaTeX spawning child processes or accessing sensitive filesystem paths that a legitimate render job would never touch.

Add the following custom Wazuh rule to your local_rules.xml to alert on suspicious XeLaTeX child process spawning and sensitive file access patterns consistent with CVE-2026-33046 exploitation:

<!-- CVE-2026-33046 Indico LaTeX RCE / LFR Detection Rules -->

<group name="indico,latex,rce,lfi,cve-2026-33046">

  <!-- Rule 1: XeLaTeX spawning a shell (shell-escape abuse) -->
  <rule id="100500" level="15">
    <if_group>syscheck</if_group>
    <field name="audit.command">xelatex|pdflatex|luatex</field>
    <field name="audit.exe">sh|bash|dash|python|python3|perl|ruby</field>
    <description>CVE-2026-33046: TeX engine spawned a shell — possible LaTeX RCE via Indico</description>
    <mitre>
      <id>T1059</id>
      <id>T1190</id>
    </mitre>
  </rule>

  <!-- Rule 2: XeLaTeX reading sensitive system files (LFR indicator) -->
  <rule id="100501" level="13">
    <if_group>syscheck</if_group>
    <field name="audit.command">xelatex|pdflatex|luatex</field>
    <field name="audit.file.name">/etc/passwd|/etc/shadow|indico\.conf|\.env|id_rsa</field>
    <description>CVE-2026-33046: TeX engine accessed sensitive file — possible LFR via Indico LaTeX renderer</description>
    <mitre>
      <id>T1083</id>
      <id>T1552.001</id>
    </mitre>
  </rule>

  <!-- Rule 3: Indico celery worker spawning unexpected child processes -->
  <rule id="100502" level="12">
    <if_group>syscheck</if_group>
    <field name="audit.ppid_name">celery</field>
    <field name="audit.exe">xelatex|pdflatex</field>
    <field name="audit.syscall">execve</field>
    <description>CVE-2026-33046: Indico Celery worker invoked TeX engine — verify this is expected rendering activity</description>
    <mitre>
      <id>T1190</id>
    </mitre>
  </rule>

</group>

To make Rule 100500 and 100501 effective, ensure your Wazuh agents have Linux Audit daemon (auditd) integration enabled and that you have audit rules watching the relevant syscalls (execve, open, openat) for the Indico service account. Here’s the corresponding auditd rule snippet to drop into /etc/audit/rules.d/indico.rules:

# Track TeX engine execution by the Indico service user
# Replace 'indico' with your actual service account name
-a always,exit -F arch=b64 -F uid=indico -S execve -k indico_exec

# Track sensitive file reads originating from the Indico service account
-a always,exit -F arch=b64 -F uid=indico -S open -S openat \
  -F path=/etc/passwd -k indico_lfi
-a always,exit -F arch=b64 -F uid=indico -S open -S openat \
  -F path=/etc/shadow -k indico_lfi
-a always,exit -F arch=b64 -F uid=indico -S open -S openat \
  -F dir=/opt/indico -F filename=indico.conf -k indico_config_read

# Load rules without reboot
# augenrules --load

These rules feed directly into Wazuh’s audit decoder pipeline. Once in place, any exploitation attempt — even against an already-patched instance someone forgot on a test server — will generate a Level 12-15 alert that your SOC can action immediately.

What to Do Right Now

🔍 Inventory all Indico instances in your environment, including test servers, internal workshop tools, and departmental deployments. Shadow-IT conference tools are common in research organizations.
⬆️ Upgrade to Indico 3.3.12 immediately. If you cannot patch today, disable XELATEX_PATH as an emergency workaround and restart the affected services.
🐳 Enable containerized LaTeX rendering via Podman post-upgrade. Container isolation is the correct long-term architectural defense for any server-side document rendering pipeline — not just for this CVE.
🔐 Audit the Indico service account’s filesystem permissions. Apply least-privilege: it should not be able to read credential files, private keys, or configs belonging to adjacent services.
📊 Deploy the Wazuh auditd rules above and validate alerting with a benign test. Confirm your SIEM ingests the indico_exec and indico_lfi audit keys.
🔎 Review historical Indico logs for anomalous PDF rendering jobs — unusually long render times, rendering errors from unexpected users, or abstract submissions containing unusual character sequences could indicate prior exploitation attempts.

The broader lesson here applies well beyond Indico: any feature that passes user-controlled content into a powerful local execution engine is a high-risk attack surface, regardless of how “niche” the syntax is. We’ve seen this pattern with Markdown renderers enabling path traversal, YAML parsers enabling deserialization, and now TeX engines enabling filesystem access. If it runs on your server and accepts user input, it deserves threat modelling — even if it’s “just for formatting abstracts.” For more context on how seemingly innocuous document and API features expand your attack surface, check out our analysis of command injection via Blinko’s test button and how headless APIs and AI agents are reshaping enterprise risk.

Original source: https://nvd.nist.gov/vuln/detail/CVE-2026-33046

📚 Related Posts

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26.04.23 02:40

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