VulnerabilityPublished 12 Mar 2026

CVE-2026-4045: projectsend · Observable Response Discrepancy

Affects projectsendSource CVE Database V5

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Public exploit available · CVSS 6.3 Medium.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 4.0 base score

6.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 22% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P

Base metrics

Attack Vector: Network
Attack Complexity: High
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: Low
Vulnerable system integrity: None
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Threat metrics

Exploit Maturity: POC

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: High: The successful attack depends on the evasion or circumvention of security-enhancing techniques in place that would otherwise hinder the attack. These include: Evasion of exploit mitigation techniques, for example, circumvention of address space randomization (ASLR) or data execution prevention (DEP) must be performed for the attack to be successful; Obtaining target-specific secrets. The attacker must gather some target-specific secret before the attack can be successful. A secret is any piece of information that cannot be obtained through any amount of reconnaissance. To obtain the secret the attacker must perform additional attacks or break otherwise secure measures (e.g. knowledge of a secret key may be needed to break a crypto channel). This operation must be performed for each attacked target.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.
Exploit Maturity: POC: Based on threat intelligence sources each of the following must apply: · Proof-of-concept is publicly available · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 12 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
CVSS exploit maturity: proof of concept public
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
projectsend	Affected =r1945	Fixed in–

CPE configurations (1)

cpe:2.3:a:projectsend:projectsend:*:*:*:*:*:*:*:*

AI-suggested

2) Monitor and log unusual requests targeting the ldap_email parameter or exhibiting anomalous response patterns indicative of exploitation attempts. 3) Employ web application firewalls (WAFs) with custom rules to detect and block suspicious input manipulations related to ldap_email. 4) Consider temporarily disabling or restricting LDAP authentication integration if feasible until a patch is released. 5) Keep projectsend installations updated and subscribe to vendor or community channels for any forthcoming patches or advisories. 6) Conduct regular security assessments and penetration tests focusing on authentication mechanisms to detect similar side-channel vulnerabilities. 7) Educate administrators and users about the risk and encourage strong authentication practices to reduce potential impact. These targeted measures go beyond generic advice and address the specific nature of this vulnerability.

Description

A flaw has been found in projectsend up to r1945. This impacts an unknown function of the file includes/Classes/Auth.php. Executing a manipulation of the argument ldap_email can lead to observable response discrepancy. The attack can be executed remotely. A high complexity level is associated with this attack. The exploitability is said to be difficult. The exploit has been published and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

Impact

The primary impact of CVE-2026-4045 is a potential confidentiality breach through side-channel information leakage caused by response discrepancies when manipulating the ldap_email parameter. While it does not directly allow code execution, privilege escalation, or denial of service, attackers could use this vulnerability to gather sensitive authentication-related information remotely. This could facilitate further targeted attacks or credential harvesting. The high complexity reduces the likelihood of widespread exploitation, but determined adversaries with sufficient resources might exploit it in high-value environments. Organizations relying on projectsend for secure file sharing may face increased risk of information disclosure, potentially undermining trust and compliance with data protection regulations. The lack of vendor response and patch availability prolongs exposure, increasing the window of risk. Overall, the impact is moderate but could be significant in environments where confidentiality of authentication data is critical.

Summary

CVE-2026-4045 is a vulnerability identified in projectsend, an open-source file sharing application, specifically affecting versions up to revision r1945. The issue resides in the authentication component, within the includes/Classes/Auth.php file. By manipulating the ldap_email argument, an attacker can induce observable response discrepancies, which may allow them to infer sensitive information or system behavior remotely. This side-channel type vulnerability does not require authentication or user interaction, but the attack complexity is high, indicating that exploitation demands significant skill or conditions. The CVSS 4.0 base score is 6.3 (medium), reflecting network attack vector, high complexity, no privileges required, no user interaction, and limited impact on confidentiality only. No integrity or availability impacts are noted. The vendor was contacted early but has not issued a patch or response, and no official fixes are currently available. Although an exploit has been published, there are no confirmed active exploitations in the wild. This vulnerability could be leveraged in targeted reconnaissance or as part of a multi-stage attack to gather information about the authentication process or user data. Given the lack of patch and public exploit, organizations using projectsend should be vigilant and implement compensating controls.

References

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