VulnerabilityPublished 22 Jan 2024Updated 30 May 2025

CVE-2024-23771: darkhttpd · Observable Discrepancy

Source CVE Database V5

Not known to be exploited · CVSS 9.8 Critical : upgrade to 1.15 as a priority.

Data as of 26 Oct 2026, 12:54 UTC

CVSS 3.1 base score

9.8Critical

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

EPSS: 1.0% chance of exploitation in 30 days – higher than 64% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.15

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

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

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: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 22 Jan 2024
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 26 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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

Upgrade emikulic/darkhttpd to 1.15.

Affected software

Product	Affected	Fixed in
GitHubemikulic/darkhttpd`pkg:github/emikulic/darkhttpd`Other threats	Affected <1.15	Fixed in 1.15

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

AI-suggested

Immediate mitigation steps include: 1) Identify and inventory all instances of darkhttpd in the environment, especially in embedded devices and lightweight web servers. 2) Where possible, upgrade to darkhttpd version 1.15 or later once available, as this version addresses the vulnerability by replacing strcmp with a constant-time comparison function. 3) If upgrading is not immediately feasible, implement network-level controls such as restricting access to darkhttpd services via firewalls or VPNs to trusted users only. 4) Employ intrusion detection systems (IDS) or anomaly detection to monitor for unusual authentication attempts or timing-based probing. 5) Consider replacing darkhttpd with alternative HTTP servers that do not have this vulnerability for critical applications. 6) Educate developers and system administrators about the risks of timing side-channel attacks and the importance of constant-time comparisons in authentication logic. 7) Regularly review and update security policies to include checks for side-channel vulnerabilities in custom or third-party software.

Description

darkhttpd before 1.15 uses strcmp (which is not constant time) to verify authentication, which makes it easier for remote attackers to bypass authentication via a timing side channel.

Impact

For European organizations, the impact of this vulnerability can be significant, especially for those using darkhttpd in critical infrastructure, IoT devices, or lightweight web services. Successful exploitation could lead to unauthorized access to internal systems, data leakage, or service disruption. This could affect sectors such as manufacturing, telecommunications, and smart city deployments where embedded HTTP servers are common. The breach of confidentiality and integrity could result in exposure of sensitive data or unauthorized control over systems, potentially leading to further lateral movement within networks. Given the critical severity and ease of exploitation, organizations face a high risk of compromise if darkhttpd is deployed without mitigation. Additionally, compliance with European data protection regulations (e.g., GDPR) could be jeopardized if personal data is exposed due to this vulnerability.

Summary

CVE-2024-23771 is a critical vulnerability affecting darkhttpd versions prior to 1.15. The issue stems from the use of the standard strcmp function for authentication verification. strcmp is not a constant-time comparison function, meaning the time it takes to compare two strings can vary depending on the number of matching characters at the start of the strings. This timing discrepancy can be exploited by remote attackers through a timing side-channel attack to bypass authentication mechanisms without needing valid credentials. Since darkhttpd is a lightweight HTTP server often used in embedded systems or simple web-serving scenarios, this vulnerability allows an attacker to gain unauthorized access remotely with no privileges or user interaction required. The CVSS 3.1 score of 9.8 reflects the high impact on confidentiality, integrity, and availability, as successful exploitation can lead to full compromise of the server. Although no known exploits are currently reported in the wild, the vulnerability is straightforward to exploit due to the lack of authentication or user interaction requirements and the network attack vector. The root cause is the use of a non-constant-time string comparison function for sensitive authentication checks, categorized under CWE-203 (Information Exposure Through Discrepancy). No patches or vendor-specific mitigations are listed, indicating that users must be vigilant and consider alternative mitigations or updates when available.

CWE-203Observable Discrepancy (opens in a new tab)
Base weakness
The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor.
Architecture and Design · Separation of Privilege
Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
Implementation
Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended).
OWASP Cheat Sheets
Error Handling (opens in a new tab)
Logging (opens in a new tab)
OWASP ASVS 4.0.3
V8.3.4 (opens in a new tab)
V14.3.3 (opens in a new tab)
V7.3.3 (opens in a new tab)
Attack patterns
Black Box Reverse Engineering (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 8 Jul 2025, 19:14 UTC

WeaknessesCWE-203

Technical details

References

Community reviews

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