CVE-2025-57785VulnerabilityPublished 26 Jan 2026

CVE-2025-57785: Hiawatha Web server · Double Free

Affects Hiawatha Web serverSource CVE Database V5

Not known to be exploited · CVSS 6.5 Medium.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

6.5Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 32% 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 26 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 2026-10-26.

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

Affected software

Product	Affected	Fixed in
HiawathaHiawatha Web server	Affected >=11.47 <=10.8.2	Fixed in–
GitHubhsleisink/hiawatha`pkg:github/hsleisink/hiawatha`Other threats	Affected =11.47	Fixed in–

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

AI-suggested

1. Immediately inventory all systems running Hiawatha web server version 11.47 to identify affected assets. 2. Monitor the Hiawatha project and trusted vulnerability databases for official patches or updates addressing CVE-2025-57785 and apply them promptly once available. 3. If patches are not yet available, consider disabling or restricting the XSLT show_index feature or any directory indexing functionality to reduce attack surface. 4. Implement network-level controls such as web application firewalls (WAFs) with custom rules to detect and block suspicious requests targeting the XSLT processing endpoints. 5. Restrict access to the web server to trusted IP ranges where feasible, especially for administrative or sensitive interfaces. 6. Employ runtime application self-protection (RASP) or endpoint detection and response (EDR) solutions to detect anomalous behavior indicative of exploitation attempts. 7. Conduct regular security audits and penetration tests focusing on web server configurations and memory corruption vulnerabilities. 8. Educate system administrators and security teams about this vulnerability to ensure rapid response and incident handling. 9. Maintain robust backup and recovery procedures to minimize impact in case of successful exploitation. 10. Consider deploying intrusion prevention systems (IPS) with updated signatures once available to detect exploitation attempts.

Description

A Double Free in XSLT `show_index` has been identified in Hiawatha webserver version 11.7 which allows an unauthenticated attacker to corrupt data which may lead to arbitrary code execution.

Impact

For European organizations, this vulnerability poses a severe risk due to the potential for remote, unauthenticated attackers to execute arbitrary code on affected servers. This could lead to data breaches, service disruptions, and lateral movement within networks. Organizations running Hiawatha web server version 11.47 in critical infrastructure, government, or enterprise environments could face significant operational and reputational damage if exploited. The ability to corrupt memory and execute code remotely compromises confidentiality, integrity, and availability of affected systems. Given the web server's role in delivering web content and applications, exploitation could also facilitate further attacks such as data exfiltration, ransomware deployment, or persistent backdoors. The lack of known exploits currently provides a window for proactive mitigation, but the ease of exploitation and unauthenticated access mean attackers may develop exploits rapidly. European entities with public-facing Hiawatha servers are particularly vulnerable, especially those in sectors with high-value targets or sensitive data.

CWE-415Double Free (opens in a new tab)
Variant weaknessLikelihood of exploit: High
The product calls free() twice on the same memory address.
Architecture and Design
Choose a language that provides automatic memory management.
Implementation
Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly.
Implementation
Use a static analysis tool to find double free instances.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

gitlab.com/hsleisink/hiawatha/-/blame/master/src/xslt.c?ref_type=heads (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Jan 2026, 18:21 UTC

WeaknessesCWE-415

Technical details

References

Community reviews

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