VulnerabilityPublished 23 Mar 2026

CVE-2026-4587: HybridAuth · Improper Certificate Validation

Affects HybridAuthSource CVE Database V5

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Not known to be exploited · CVSS 6.3 Medium.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score

6.3Medium

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 8% 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:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X

Attack Vector: Network
Attack Complexity: High
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: None
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: 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: None: There is no loss of confidentiality within 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 23 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 30 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
HybridAuth	Affected =3.12.0 =3.12.1 =3.12.2	Fixed in–
GitHubhybridauth/hybridauth`pkg:github/hybridauth/hybridauth`Other threats	Affected =3.12.0 =3.12.1 =3.12.2	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

To mitigate CVE-2026-4587, organizations should first verify if they are using HybridAuth versions 3.12.0, 3.12.1, or 3.12.2 and plan to upgrade to a patched version once available. In the absence of an official patch, immediate mitigation steps include: 1) Manually auditing and enforcing strict SSL certificate validation in the Curl.php component by overriding or sanitizing curlOptions to ensure CURLOPT_SSL_VERIFYPEER and CURLOPT_SSL_VERIFYHOST are properly set to enforce verification. 2) Employing network-level protections such as TLS interception detection, strict transport security (HSTS), and certificate pinning where feasible to reduce MITM risks. 3) Monitoring network traffic for anomalies indicative of MITM attacks. 4) Restricting access to authentication endpoints via IP whitelisting or VPNs to reduce exposure. 5) Encouraging users to use multi-factor authentication (MFA) to mitigate risks from credential compromise. 6) Keeping all related dependencies and server software up to date to minimize attack surface. Finally, maintain close communication with the HybridAuth project for updates and patches.

Description

A vulnerability was found in HybridAuth up to 3.12.2. This issue affects some unknown processing of the file src/HttpClient/Curl.php of the component SSL Handler. The manipulation of the argument curlOptions results in improper certificate validation. The attack can be launched remotely. This attack is characterized by high complexity. The exploitability is assessed as difficult. The project was informed of the problem early through an issue report but has not responded yet.

Impact

The primary impact of CVE-2026-4587 is on the confidentiality and integrity of data transmitted via HybridAuth during authentication processes. Successful exploitation could enable attackers to intercept authentication tokens, user credentials, or other sensitive information by conducting man-in-the-middle attacks. This could lead to unauthorized access to user accounts or impersonation attacks, undermining trust in authentication mechanisms. Since HybridAuth is widely used in web applications to facilitate social logins, organizations relying on affected versions may face increased risk of credential theft or session hijacking. The vulnerability does not affect availability directly but could indirectly cause service disruptions if exploited or if mitigations require downtime. The difficulty of exploitation reduces immediate risk, but the lack of vendor response and patches increases the window of exposure. Organizations with high volumes of user authentication traffic or those handling sensitive user data are particularly vulnerable to reputational damage and regulatory consequences if this vulnerability is exploited.

Summary

CVE-2026-4587 is a vulnerability identified in HybridAuth, a popular PHP library used for social login and authentication integration, affecting versions 3.12.0 through 3.12.2. The issue resides in the SSL Handler component, specifically in the src/HttpClient/Curl.php file, where improper handling and validation of SSL certificates occur due to manipulation of the curlOptions argument. This improper certificate validation means that when HybridAuth establishes HTTPS connections, it may fail to correctly verify the authenticity of SSL certificates presented by remote servers. Consequently, an attacker capable of intercepting network traffic could exploit this flaw to perform man-in-the-middle (MITM) attacks, potentially intercepting or modifying sensitive authentication tokens or user credentials. The vulnerability is exploitable remotely without requiring authentication or user interaction, but the attack complexity is high, making exploitation difficult. The CVSS v4.0 score is 6.3 (medium severity), reflecting the moderate impact on confidentiality and integrity, with no impact on availability. The vendor has been notified but has not yet issued a patch or response. No known exploits have been observed in the wild to date. This vulnerability highlights the critical importance of proper SSL certificate validation in authentication libraries to prevent interception and tampering of sensitive data.

References

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