Lychee: Improper Restriction of Excessive Authentication Attempts
CVE-2026-61611 is a high-severity improper restriction of excessive authentication attempts vulnerability in Lychee from LycheeOrg, 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 Lychee versions: < 7.6.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.45% 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
- Check which version of Lychee you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.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
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
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. Scored by CNA (github.com).
Official description
Lychee is a free, open-source photo-management tool. Prior to 7.6.1, POST /api/v2/Album::unlock has no throttle, attempt counter, backoff, CAPTCHA, or lockout. UnlockAlbumRequest::authorize() permits any caller to submit attempts, and app/Actions/Album/Unlock.php verifies each guess with Hash::check without limiting repeated failures. A remote unauthenticated attacker who knows or can obtain an album identifier can automate password guesses against a password-protected album and, if the password is recovered, gain access to its private photo collection. This issue is fixed in version 7.6.1.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Restriction of Excessive Authentication Attempts
The product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame.
How developers prevent this class of flaw
- Common protection mechanisms include: Disconnecting the user after a small number of failed attempts Implementing a timeout Locking out a targeted account Requiring a computational task on the user's part.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator.
More Improper Restriction of Excessive Authentication Attempts vulnerabilities (CWE-307)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other vulnerabilities in Lychee
- 8.3 High severity
- 7.1 High severity
- 8.3 High severity
- 8.9 High severity
- 8.2 High severity
- 7.5 High severity
Recent Improper Restriction of Excessive Authentication Attempts vulnerabilities
- 7.4 High severity
- 8.1 High severity
- 8.1 High severity
- 7.4 High severity
- 9.1 Critical severity
- 9.8 Critical severity
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