VulnerabilityPublished 22 Oct 2026Updated 30 Oct 2026

CVE-2026-94140: Rex versions through 1.16.1 for Perl accept an unknown SSH host key for remote rsync transfers

Source GCVE Database

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Authoritative record:CVE-2026-94140· Critical 9.1

Not known to be exploited · CVSS 9.1 Critical.

Data as of 30 Oct 2026, 21:05 UTC

CVSS 3.1 base score

9.1Critical

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

Thin evidence

One scorer or none

CVSS scores by source
CISA-ADP	CVSS 3.1	9.1

EPSS: 0.2% chance of exploitation in 30 days – higher than 16% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
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: None: The vulnerable system can be exploited without any interaction from any user.
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: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to 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 21 Oct 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.

ghsa-xx8j-qhmg-cj8f

What to do

Affected software

Product	Affected	Fixed in
Rex	Affected <=1.16.1	Fixed in–
CPANRex`pkg:cpan/Rex`Other threats	Affected <=1.16.1	Fixed in–

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

AI-suggested

Until a fix is available, avoid using vulnerable versions of Rex for remote rsync transfers or use alternative secure transfer methods that enforce SSH host key verification. Monitor vendor communications for updates and patches addressing this issue.

Description

Rex versions through 1.16.1 for Perl contain a vulnerability where the SSH host key verification is disabled (StrictHostKeyChecking=no) for remote rsync transfers. This allows an attacker who can intercept or redirect the connection to present a malicious SSH host key, causing the client to accept it without verification. Consequently, sensitive data such as passwords can be exposed, and files can be uploaded or downloaded to an attacker-controlled server.

Impact

An attacker who can redirect the SSH connection can impersonate the remote host by presenting a malicious SSH host key. This results in the client accepting the attacker as the legitimate server without verification. Under password authentication, the client sends the password to the attacker. Additionally, the attacker can cause arbitrary files to be uploaded from or downloaded to the client, compromising confidentiality and integrity of data. The vulnerability has a CVSS 3.1 score of 9.1 (critical), indicating high impact on confidentiality and integrity without requiring privileges or user interaction.

Summary

Rex versions up to 1.16.1 for Perl have a security flaw in their remote rsync transfer implementation. The sync function hardcodes the SSH option StrictHostKeyChecking=no, disabling host key verification. This applies to all remote sync branches, including password and private-key authentication. Attempts to override this behavior via set_openssh_opt do not affect the sync command, leaving no way to enforce host key checking. An attacker capable of redirecting the SSH connection can present a rogue host key, causing the client to trust it. This leads to potential credential exposure during password authentication and unauthorized file uploads or downloads.

CWE-322Key Exchange without Entity Authentication (opens in a new tab)
Base weaknessLikelihood of exploit: HighOWASP Top 10 A04:2025: Cryptographic Failures (opens in a new tab)
The product performs a key exchange with an actor without verifying the identity of that actor.
Architecture and Design
Ensure that proper authentication is included in the system design.
Implementation
Understand and properly implement all checks necessary to ensure the identity of entities involved in encrypted communications.
OWASP Cheat Sheets
Transport Layer Protection (opens in a new tab)
User Privacy Protection (opens in a new tab)
Password Storage (opens in a new tab)
Cryptographic Storage (opens in a new tab)
HSTS (opens in a new tab)
OWASP ASVS 4.0.3
V1.2.3 (opens in a new tab)
V1.2.2 (opens in a new tab)
V1.2.4 (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 30 Oct 2026, 21:05 UTC

WeaknessesCWE-322

Technical details

References

Community reviews

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