modu680-AS: Time-of-check Time-of-use (TOCTOU) Race Condition
CVE-2026-78319 is a critical-severity time-of-check time-of-use (TOCTOU) race condition vulnerability in modu680-AS from Sauter, with a CVSS 4.0 base score of 9.3 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 4.0.0 as the first without the flaw, so updating modu680-AS to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.61% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update modu680-AS to 4.0.0 or a later version.
- Update modu660-AS to 4.0.0 or a later version.
- Update modu612-LC to 4.0.0 or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Sauter | modu680-AS | 1.0.0 up to, but not including, 4.0.0 | 4.0.0 |
| Sauter | modu660-AS | 1.0.0 up to, but not including, 4.0.0 | 4.0.0 |
| Sauter | modu612-LC | 1.0.0 up to, but not including, 4.0.0 | 4.0.0 |
| Sauter | ecos504 | 1.0.0 up to, but not including, 7.0.0 | 7.0.0 |
| Sauter | ecos505 | 1.0.0 up to, but not including, 7.0.0 | 7.0.0 |
Version data comes from the organisation that assigned the CVE. 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.
- Attack requirements
- NoneThe attack does not depend on a particular deployment or configuration.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Confidentiality (vulnerable system)
- HighSerious loss of confidentiality on the vulnerable system.
- Integrity (vulnerable system)
- HighSerious loss of integrity on the vulnerable system.
- Availability (vulnerable system)
- HighSerious loss of availability on the vulnerable system.
- Confidentiality (other systems)
- NoneNo loss of confidentiality on systems beyond the vulnerable one.
- Integrity (other systems)
- NoneNo loss of integrity on systems beyond the vulnerable one.
- Availability (other systems)
- NoneNo loss of availability on systems beyond the vulnerable one.
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/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:X/V:X/RE:X/U:X. Scored by CNA (cert.vde.com).
Official description
A service running on the affected products contains a potential Time-of-Check Time-of-Use (TOCTOU) race condition. An unauthenticated remote attacker could exploit this race condition to bypass intended security controls. This may result in the execution of unauthorized code.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Time-of-check Time-of-use (TOCTOU) Race Condition
The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.
How developers prevent this class of flaw
- The most basic advice for TOCTOU vulnerabilities is to not perform a check before the use. This does not resolve the underlying issue of the execution of a function on a resource whose state and identity cannot be assured, but it does help to limit the false sense of security given by the check.
- When the file being altered is owned by the current user and group, set the effective gid and uid to that of the current user and group when executing this statement.
- Limit the interleaving of operations on files from multiple processes.
More Time-of-check Time-of-use (TOCTOU) Race Condition vulnerabilities (CWE-367)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
Recent Time-of-check Time-of-use (TOCTOU) Race Condition vulnerabilities
- 7.5 High severity
- 7.3 High severity
- 8.1 High severity
- 7.8 High severity
- 8.1 High severity
- 8.1 High severity
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