CVE-2025-40918VulnerabilityPublished 16 Jul 2025Updated 4 Nov 2025

CVE-2025-40918: EHUELS Authen::SASL::Perl::DIGEST_MD5 · Generation of Predictable Numbers or Identifiers

Affects EHUELS Authen::SASL::Perl::DIGEST_MD5Source CVE Database V5

Not known to be exploited · CVSS 6.5 Medium.

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: 0.4% chance of exploitation in 30 days – higher than 38% 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:L/I:L/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
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: 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 impacted component.
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 on 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 16 Jul 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 2026-10-25.

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.

cwe-338

What to do

Affected software

Product	Affected	Fixed in
EHUELS Authen::SASL::Perl::DIGEST_MD5	Affected =2.04	Fixed in–

AI-suggested

To mitigate this vulnerability, organizations should: 1) Upgrade the Authen::SASL::Perl::DIGEST_MD5 module to a version that addresses the cnonce generation issue once available. 2) If no patched version exists, implement custom patches or wrappers that replace the insecure cnonce generation with a cryptographically secure random number generator, such as using Perl modules like Crypt::PRNG or Crypt::Random to generate at least 64 bits of entropy. 3) Review and harden SASL authentication configurations to prefer stronger mechanisms than DIGEST_MD5 where possible, such as SCRAM or external authentication methods. 4) Monitor network traffic for suspicious authentication attempts or replay attacks targeting DIGEST_MD5 sessions. 5) Educate developers and system administrators about the risks of using non-cryptographically secure random functions in security-sensitive contexts. 6) Consider deploying additional network-level protections such as TLS to protect authentication exchanges from interception and manipulation.

Description

Authen::SASL::Perl::DIGEST_MD5 versions 2.04 through 2.1800 for Perl generates the cnonce insecurely. The cnonce (client nonce) is generated from an MD5 hash of the PID, the epoch time and the built-in rand function. The PID will come from a small set of numbers, and the epoch time may be guessed, if it is not leaked from the HTTP Date header. The built-in rand function is unsuitable for cryptographic usage. According to RFC 2831, The cnonce-value is an opaque quoted string value provided by the client and used by both client and server to avoid chosen plaintext attacks, and to provide mutual authentication. The security of the implementation depends on a good choice. It is RECOMMENDED that it contain at least 64 bits of entropy.

Impact

For European organizations, this vulnerability could lead to compromised authentication sessions where attackers predict or replay the cnonce, enabling them to intercept or manipulate authentication exchanges. This can result in unauthorized access to sensitive systems or data, undermining confidentiality and integrity. Organizations using Perl-based authentication mechanisms, especially those relying on the Authen::SASL::Perl::DIGEST_MD5 module in legacy or custom applications, are at risk. The vulnerability could affect web services, mail servers, or other networked applications employing DIGEST_MD5 SASL authentication. Given the medium severity, the impact is significant but not catastrophic; however, in high-security environments such as government, finance, or critical infrastructure sectors, even partial compromise of authentication can have serious consequences. The lack of known exploits in the wild suggests a window for proactive mitigation before widespread exploitation occurs.

CWE-340Generation of Predictable Numbers or Identifiers (opens in a new tab)
Class weaknessOWASP Top 10 A04:2025: Cryptographic Failures (opens in a new tab)
The product uses a scheme that generates numbers or identifiers that are more predictable than required.
OWASP Cheat Sheets
Forgot Password (opens in a new tab)
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)
OWASP ASVS 4.0.3
V2.3.1 (opens in a new tab)
V2.6.2 (opens in a new tab)
V2.7.6 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 4 Nov 2025, 21:48 UTC

WeaknessesCWE-340

Technical details

References

Community reviews

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