Apache Directory LDAP API: Asymmetric Resource Consumption (Amplification)
CVE-2026-103880 is a high-severity asymmetric resource consumption (amplification) vulnerability in Apache Directory LDAP API from Apache, 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. The record lists version 2.1.9 as the first without the flaw, so updating Apache Directory LDAP API to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.43% 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 Apache Directory LDAP API to 2.1.9 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 |
|---|---|---|---|
| Apache | Apache Directory LDAP API | 2.1.0 up to, but not including, 2.1.9 | 2.1.9 |
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 CISA (ADP).
Official description
Asymmetric Resource Consumption vulnerability in Apache Directory LDAP API. Storing a password using the bcrypt algorithm with a high force like 30 in a LDAP server that supports this algorithm will cause the server CPU to run for hours checking the credentials. A bounded cost should be enforced to avoid a server DOS. This issue affects Apache Directory LDAP API: from 2.1.0 before 2.1.9. Users are recommended to upgrade to version 2.1.9, which fixes the issue.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Asymmetric Resource Consumption (Amplification)
The product does not properly control situations in which an adversary can cause the product to consume or produce excessive resources without requiring the adversary to invest equivalent work or otherwise prove authorization, i.e., the adversary's influence is asymmetric.
How developers prevent this class of flaw
- An application must make resources available to a client commensurate with the client's access level.
- An application must, at all times, keep track of allocated resources and meter their usage appropriately.
- Consider disabling resource-intensive algorithms on the server side, such as Diffie-Hellman key exchange.
More Asymmetric Resource Consumption (Amplification) vulnerabilities (CWE-405)
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 references
Other vulnerabilities in Apache Directory LDAP API
- 7.5 High severity
- 7.5 High severity
- 9.8 Critical severity
- 7.3 High severity
- 7.5 High severity
- 8.5 High severity
Recent Asymmetric Resource Consumption (Amplification) vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
Spotted an error? Tell us.