VulnerabilityPublished 20 Mar 2026

CVE-2026-32881: vshakitskiy ewe · Permissive List of Allowed Inputs

Affects vshakitskiy eweSource CVE Database V5

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Not known to be exploited · CVSS 5.3 Medium : upgrade to 3.0.5 when convenient.

Data as of 1 Nov 2026, 08:20 UTC

CVSS 3.1 base score

5.3Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 33% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.0.5, 3.0

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
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: None: There is no loss of confidentiality within 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 20 Mar 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 31 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.

What to do

Upgrade ewe to 3.0.5; vshakitskiy/ewe to 3.0.

Affected software

Product	Affected	Fixed in
vshakitskiyewe	Affected >=0.6.0 <3.0.5	Fixed in 3.0.5
GitHubvshakitskiy/ewe`pkg:github/vshakitskiy/ewe`Other threats	Affected <3.0	Fixed in 3.0

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

AI-suggested

Organizations should immediately upgrade the ewe web server to version 3.0.5 or later, where this vulnerability is patched. Until the upgrade can be performed, administrators should implement strict input validation and filtering on incoming HTTP requests, particularly scrutinizing chunked transfer encoding trailers. Deploying Web Application Firewalls (WAFs) with custom rules to detect and block suspicious Trailer headers or unusual chunked transfer encoding usage can help mitigate exploitation attempts. Reverse proxies and middleware should be configured to ignore or sanitize headers originating from untrusted sources, especially those that influence authentication or proxy trust decisions. Logging and monitoring HTTP headers for anomalies post body parsing can provide early detection of exploitation attempts. Additionally, organizations should review their authentication and session management mechanisms to ensure they are resilient against header spoofing. Conducting penetration testing focused on chunked transfer encoding handling can identify residual risks. Finally, maintain awareness of updates from the ewe project and related security advisories.

Description

CVE-2026-32881 affects the Gleam web server 'ewe' versions 0.6.0 through 3.0.4 and allows attackers to bypass authentication or spoof proxy-trust headers by exploiting permissive handling of chunked transfer encoding trailers. The vulnerability arises because only a limited denylist of nine header names is blocked when merging trailer headers into the request headers after body parsing. Malicious clients can append headers in the Trailer field after the final chunk, causing legitimate headers to be overwritten. This enables forging authentication credentials, session hijacking, bypassing IP-based rate limiting, or spoofing proxy-trust headers in downstream middleware that reads headers post body parsing. The issue is fixed in version 3.0.

Impact

This vulnerability can have significant impacts on organizations using the vulnerable versions of the ewe web server. Attackers can bypass authentication mechanisms, leading to unauthorized access to protected resources. Session hijacking can compromise user accounts and sensitive data. Spoofing proxy-trust headers can mislead downstream middleware into trusting malicious requests, potentially escalating privileges or bypassing security controls such as IP-based rate limiting. This can facilitate further attacks like brute force, credential stuffing, or lateral movement within networks. Although confidentiality is not directly affected, the integrity and availability of services can be compromised. Organizations relying on ewe for web services, especially those deploying reverse proxies or middleware that trust headers, are at risk. The ease of exploitation without authentication or user interaction increases the threat level. If exploited in critical infrastructure or high-value targets, the consequences could be severe, including data breaches, service disruption, and reputational damage.

CWE-183Permissive List of Allowed Inputs (opens in a new tab)
Base weaknessOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are explicitly allowed by policy because the inputs are assumed to be safe, but the list is too permissive - that is, it allows an input that is unsafe, leading to resultant weaknesses.
OWASP Cheat Sheets
Secure Design Principles (opens in a new tab)
Attack patterns
Double Encoding (opens in a new tab)
Using Leading 'Ghost' Character Sequences to Bypass Input Filters (opens in a new tab)
Exploiting Multiple Input Interpretation Layers (opens in a new tab)
Using Unicode Encoding to Bypass Validation Logic (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 27 Mar 2026, 19:34 UTC

WeaknessesCWE-183

Technical details

References

Community reviews

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