CVE-2026-22689VulnerabilityPublished 10 Jan 2026Updated 12 Jan 2026

CVE-2026-22689: axllent mailpit · Missing Origin Validation in WebSockets

Affects axllent mailpitSource CVE Database V5

Not known to be exploited · CVSS 6.5 Medium : upgrade to 1.28.2 when convenient.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

6.5Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 14% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.28.2

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

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

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, 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: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 10 Jan 2026
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 2026-10-25.

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

Upgrade mailpit and axllent/mailpit to 1.28.2.

Affected software

Product	Affected	Fixed in
axllentmailpit	Affected <1.28.2	Fixed in 1.28.2
GitHubaxllent/mailpit`pkg:github/axllent/mailpit`Other threats	Affected <1.28.2	Fixed in 1.28.2

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

AI-suggested

The primary mitigation is to upgrade Mailpit to version 1.28.2 or later, where the Origin header validation is properly implemented. Until upgrading, organizations should restrict developer access to untrusted websites to reduce the risk of CSWSH attacks. Developers should avoid visiting unknown or suspicious websites while running vulnerable Mailpit versions locally. Network-level controls can be implemented to block outbound WebSocket connections from localhost to external origins. Additionally, configuring local firewalls or endpoint protection solutions to monitor and restrict WebSocket traffic can help mitigate exploitation. Security awareness training should emphasize the risks of visiting untrusted sites during development activities. Organizations should also audit their development environments to identify any instances of vulnerable Mailpit versions and ensure timely patching. Finally, consider isolating development environments or using containerized setups to limit exposure.

Description

Mailpit is an email testing tool and API for developers. Prior to version 1.28.2, the Mailpit WebSocket server is configured to accept connections from any origin. This lack of Origin header validation introduces a Cross-Site WebSocket Hijacking (CSWSH) vulnerability. An attacker can host a malicious website that, when visited by a developer running Mailpit locally, establishes a WebSocket connection to the victim's Mailpit instance (default ws://localhost:8025). This allows the attacker to intercept sensitive data such as email contents, headers, and server statistics in real-time. This issue has been patched in version 1.28.2.

Impact

For European organizations, this vulnerability poses a significant risk to development environments where Mailpit is used for email testing. Sensitive email data, including contents and headers, could be exposed to attackers if developers visit malicious websites while running vulnerable Mailpit versions locally. This can lead to leakage of confidential information, potentially including internal communications or test data that may contain sensitive or proprietary information. Although the vulnerability does not directly impact production systems or server availability, the confidentiality breach could facilitate further attacks or data leaks. Organizations with remote or hybrid workforces may face increased risk due to varied browsing habits. The impact is particularly relevant for software development companies, IT service providers, and any organization relying on Mailpit for email testing and development workflows. Failure to patch could also undermine compliance with data protection regulations such as GDPR, given the potential exposure of personal data in emails.

CWE-1385Missing Origin Validation in WebSockets (opens in a new tab)
Variant weakness
The product uses a WebSocket, but it does not properly verify that the source of data or communication is valid.
Implementation
Enable CORS-like access restrictions by verifying the 'Origin' header during the WebSocket handshake.
Implementation
Use a randomized CSRF token to verify requests.
Implementation
Use TLS to securely communicate using 'wss' (WebSocket Secure) instead of 'ws'.
OWASP ASVS 4.0.3
V14.5.2 (opens in a new tab)
V14.5.3 (opens in a new tab)
V1.4.4 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 17 Jan 2026, 07:54 UTC

WeaknessesCWE-1385

Technical details

References

Community reviews

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