Exim SMTP Challenge stack-based overflow

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
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CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
8.6$0-$5k0.00

Summaryinfo

A vulnerability was found in Exim and classified as critical. Affected by this vulnerability is an unknown functionality of the component SMTP Challenge. Executing a manipulation can lead to stack-based overflow. This vulnerability is registered as CVE-2023-42116. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability has been found in Exim (Mail Server Software) (the affected version is unknown) and classified as critical. This vulnerability affects an unknown code of the component SMTP Challenge. The manipulation with an unknown input leads to a stack-based overflow vulnerability. The CWE definition for the vulnerability is CWE-121. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function). As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

Exim SMTP Challenge Stack-based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Exim. Authentication is not required to exploit this vulnerability. The specific flaw exists within the handling of NTLM challenge requests. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a fixed-length stack-based buffer. An attacker can leverage this vulnerability to execute code in the context of the service account. . Was ZDI-CAN-17515.

The weakness was published 09/28/2023 as ZDI-23-1470. The advisory is available at zerodayinitiative.com. This vulnerability was named CVE-2023-42116 since 09/06/2023. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 08/07/2025).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

Name

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.7
VulDB Meta Temp Score: 8.6

VulDB Base Score: 8.1
VulDB Temp Score: 7.8
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 9.8
NVD Vector: 🔍

CNA Base Score: 8.1
CNA Vector: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

Class: Stack-based overflow
CWE: CWE-121 / CWE-119
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔍

Timelineinfo

09/06/2023 🔍
09/28/2023 +22 days 🔍
09/28/2023 +0 days 🔍
08/07/2025 +679 days 🔍

Sourcesinfo

Advisory: ZDI-23-1470
Status: Not defined

CVE: CVE-2023-42116 (🔍)
GCVE (CVE): GCVE-0-2023-42116
GCVE (VulDB): GCVE-100-240790

Entryinfo

Created: 09/28/2023 07:49
Updated: 08/07/2025 23:35
Changes: 09/28/2023 07:49 (37), 09/19/2024 11:45 (27), 08/07/2025 23:35 (11)
Complete: 🔍
Cache ID: 216::103

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