lam: Incorrect Regular Expression
CVE-2026-27895 is a high-severity incorrect regular expression vulnerability in lam from LDAPAccountManager, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected lam versions: < 9.5. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.49% 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 LDAP Account Manager to 9.5 or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| LDAPAccountManager | lam | < 9.5 | Not stated |
| Ldap-account-manager | LDAP Account Manager | 8.5 up to, but not including, 9.5 | 9.5 |
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
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- 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
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 4.3 | Medium | CNA (github.com) |
| CVSS 3.1 | 8.8 | High | NVD |
Official description
LDAP Account Manager (LAM) is a webfrontend for managing entries (e.g. users, groups, DHCP settings) stored in an LDAP directory. Prior to version 9.5, the PDF export component does not correctly validate uploaded file extensions. This way any file type (including .php files) can be uploaded. With GHSA-w7xq-vjr3-p9cf, an attacker can achieve remote code execution as the web server user. Version 9.5 fixes the issue. Although upgrading is recommended, a workaround would be to make /var/lib/ldap-account-manager/config read-only for the web-server user.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Incorrect Regular Expression
The product specifies a regular expression in a way that causes data to be improperly matched or compared.
How developers prevent this class of flaw
- Regular expressions can become error prone when defining a complex language even for those experienced in writing grammars. Determine if several smaller regular expressions simplify one large regular expression. Also, subject the regular expression to thorough testing techniques such as equivalence partitioning, boundary value analysis, and robustness. After testing and a reasonable confidence level is achieved, a regular expression may not be foolproof. If an exploit is allowed to slip through, then record the exploit and refactor the regular expression.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Patches and release notes
Other vulnerabilities in lam
- 8.8 High severity
- 7.8 High severity
- 8.8 High severity
- 8.1 High severity
Recent Incorrect Regular Expression vulnerabilities
- 9.3 Critical severity
- 7.5 High severity
- 9.8 Critical severity
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