Commvault Cloud: Stack-based Buffer Overflow
CVE-2026-77101 is a high-severity stack-based buffer overflow vulnerability in Commvault Cloud from Commvault, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Commvault Cloud versions: 11.46.0 through 11.46.19; 11.44.0 through 11.44.19; 11.40.0 through 11.40.71, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.46% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Commvault to 11.36.123 or 11.40.72 or 11.44.20 or 11.46.20, whichever matches your release line, or a later version.
- Read the advisory on documentation.commvault.com for workarounds and exact fixed builds.
- 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 |
|---|---|---|---|
| Commvault | Commvault Cloud | 11.46.0 through 11.46.19; 11.44.0 through 11.44.19; 11.40.0 through 11.40.71; 11.36.0 through 11.36.122 | Not stated |
| Commvault | Commvault | 11.36.0 up to, but not including, 11.36.123; 11.40.0 up to, but not including, 11.40.72; 11.44.0 up to, but not including, 11.44.20; 11.46.0 up to, but not including, 11.46.20 | 11.36.123, 11.40.72, 11.44.20, 11.46.20 |
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.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.7 | High | CNA |
| CVSS 3.1 | 7.5 | High | NVD |
Official description
CommServe contained a stack-based buffer overflow issue affecting service availability. Software customers upgrade to resolved maintenance release. Update CommServe.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Stack-based Buffer Overflow
The product writes past the end of a buffer that was allocated on the stack.
How developers prevent this class of flaw
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
- Use an abstraction library to abstract away risky APIs. Not a complete solution.
- Implement and perform bounds checking on input.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in Commvault Cloud
- 8.7 High severity
- 7.1 High severity
- 8.7 High severity
- 7.7 High severity
- 7.1 High severity
- 7.1 High severity
Recent Stack-based Buffer Overflow vulnerabilities
- 8.5 High severity
- 9.1 Critical severity
- 9.1 Critical severity
- 8.2 High severity
- 9.8 Critical severity
- 9.8 Critical severity
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