CVE-2023-53878VulnerabilityPublished 15 Dec 2025

CVE-2023-53878: Phpjabbers Member Login Script · HTTP Request/Response Smuggling

Affects Phpjabbers Member Login ScriptSource CVE Database V5

Not known to be exploited · CVSS 7.3 High.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 4.0 base score

7.3High

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

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

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

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

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: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
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: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to 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.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 15 Dec 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
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), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.

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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC 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
Phpjabbers Member Login Script	Affected =3.3	Fixed in–

AI-suggested

1. Monitor Phpjabbers official channels for security patches addressing CVE-2023-53878 and apply them immediately upon release. 2. Implement strict HTTP header validation on web servers and reverse proxies to detect and reject malformed or suspicious Content-Length headers. 3. Deploy Web Application Firewalls (WAFs) with capabilities to detect and block HTTP request smuggling attempts, including anomalies in request parsing and header inconsistencies. 4. Conduct thorough security testing, including fuzzing and penetration testing focused on HTTP request handling, to identify and remediate similar desynchronization issues. 5. Segment web application infrastructure to limit the impact of potential exploitation and monitor logs for unusual request patterns indicative of smuggling attacks. 6. Educate development and operations teams about HTTP request smuggling risks and ensure secure coding practices for HTTP header processing. 7. Consider upgrading to newer, secure versions of the Member Login Script or alternative solutions if patches are delayed or unavailable.

Description

CVE-2023-53878 is a high-severity HTTP request smuggling vulnerability in Phpjabbers Member Login Script version 3.3. It arises from inconsistent parsing of the Content-Length header, allowing attackers to craft malicious POST requests that desynchronize client-server HTTP request handling. This can enable attackers to bypass server-side request processing controls, potentially leading to unauthorized actions or data exposure. The vulnerability requires no authentication or user interaction and can be exploited remotely over the network. Although no known exploits are currently reported in the wild, the vulnerability's nature and CVSS score of 7.3 indicate a significant risk. European organizations using this script, especially those in sectors relying on web-based member authentication, could face targeted attacks. Mitigation involves applying patches once available, implementing strict HTTP header validation, and deploying web application firewalls with request smuggling detection capabilities. Countries with higher adoption of Phpjabbers products and critical web infrastructure are at greater risk.

Impact

For European organizations, exploitation of CVE-2023-53878 could lead to unauthorized access to member accounts, data leakage, and potential manipulation of web application behavior. This is particularly critical for sectors such as finance, healthcare, education, and e-commerce, where member login scripts protect sensitive personal or financial data. Attackers could bypass authentication mechanisms or inject malicious requests that compromise user sessions or escalate privileges. The vulnerability could also be used as a foothold for further attacks within the network. Given the remote exploitability and lack of required authentication, attackers can target vulnerable web servers directly from the internet. The impact on confidentiality and integrity is high, while availability impact is limited. Organizations relying on Phpjabbers Member Login Script 3.3 without mitigations are at risk of data breaches, reputational damage, and regulatory penalties under GDPR if personal data is compromised.

Summary

CVE-2023-53878 is a vulnerability classified as HTTP request smuggling affecting Phpjabbers Member Login Script version 3.3. The root cause is an inconsistent interpretation of HTTP requests between client and server, specifically related to the parsing of the Content-Length header. HTTP request smuggling occurs when an attacker crafts a single HTTP request that is interpreted differently by front-end and back-end servers, allowing the attacker to 'smuggle' a secondary request that bypasses normal security controls. In this case, the vulnerability is client-side desynchronization, meaning the client and server disagree on where one request ends and another begins due to malformed Content-Length headers. This can lead to the attacker injecting unauthorized requests, bypassing authentication or access controls, or manipulating server-side logic. The vulnerability does not require authentication or user interaction, making it remotely exploitable over the network. The CVSS 4.0 score of 7.3 (high) reflects the ease of exploitation (network vector, low attack complexity) and the impact on confidentiality and integrity, though availability impact is low. No patches or known exploits are currently documented, but the vulnerability's nature suggests it could be leveraged for session hijacking, unauthorized data access, or web cache poisoning. The affected product is a web-based member login script, commonly used in membership or subscription websites, which increases the risk of sensitive data exposure or unauthorized account access if exploited.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 22 Dec 2025, 21:51 UTC

Technical details

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