CyberSecBulletin
CVE-2025-66834NVD status: Analyzed

Trueconf Server: Improper Neutralization of Formula Elements in a CSV File

Published Updated By the CyberSecBulletin desk

CVE-2025-66834 is a high-severity improper neutralization of formula elements in a CSV file vulnerability in Trueconf Server from TrueConf, with a CVSS 3.1 base score of 7.3 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, but only if a user takes part, for example by opening a link or file. Affected Trueconf Server versions: 5.5.2.10813. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.31% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of Trueconf Server you run against the affected versions below, and install the vendor's latest release.
  2. Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.

Affected products and versions

VendorProductAffected versionsFixed in
TrueconfTrueconf Server5.5.2.10813Not stated

Version data comes from NVD's product matching. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
RequiredA user must take an action such as opening a file or link.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
NoneAvailability is not affected.

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N. Scored by CISA (ADP).

Official description

A CSV Formula Injection vulnerability in TrueConf Server v5.5.2.10813 allows a normal user to inject malicious spreadsheet formulas into exported chat logs via crafted Display Name.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Neutralization of Formula Elements in a CSV File

The product saves user-provided information into a Comma-Separated Value (CSV) file, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as a command when the file is opened by a spreadsheet product.

How developers prevent this class of flaw

  • When generating CSV output, ensure that formula-sensitive metacharacters are effectively escaped or removed from all data before storage in the resultant CSV. Risky characters include '=' (equal), '+' (plus), '-' (minus), and '@' (at).
  • If a field starts with a formula character, prepend it with a ' (single apostrophe), which prevents Excel from executing the formula.
  • Certain implementations of spreadsheet software might disallow formulas from executing if the file is untrusted, or if the file is not authored by the current user.

More Improper Neutralization of Formula Elements in a CSV File vulnerabilities (CWE-1236)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Technical write-ups (may include proof of concept)

Other references

Other vulnerabilities in Trueconf Server

All Trueconf Server vulnerabilities

Recent Improper Neutralization of Formula Elements in a CSV File vulnerabilities

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