VulnerabilityPublished 10 Mar 2026

CVE-2026-31808: sindresorhus file-type · Infinite Loop

Affects sindresorhus file-typeSource CVE Database V5

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Not known to be exploited · CVSS 5.3 Medium : upgrade to 21.3.1 when convenient.

Data as of 29 Oct 2026, 19:04 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 27% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 21.3.1

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

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

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: None: There is no loss of integrity within the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 10 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 29 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 sindresorhus file-type to 21.3.1.

Affected software

Product	Affected	Fixed in
sindresorhusfile-type	Affected >=13.0.0 <21.3.1	Fixed in 21.3.1

AI-suggested

To mitigate this vulnerability, organizations should upgrade the sindresorhus file-type library to version 21.3.1 or later, where the infinite loop issue is fixed. For environments where immediate upgrade is not feasible, implementing input validation to detect and reject malformed ASF files with zero-sized sub-headers can help reduce risk. Additionally, applying timeouts or watchdog mechanisms on file processing routines can prevent indefinite blocking of the Node.js event loop. Employing sandboxing or resource limiting for file parsing operations can also contain the impact of potential infinite loops. Monitoring application logs for repeated parsing failures or unusually long processing times may help detect exploitation attempts. Finally, restricting exposure of file-type detection services to trusted sources or behind authentication can reduce attack surface.

Description

file-type detects the file type of a file, stream, or data. Prior to 21.3.1, a denial of service vulnerability exists in the ASF (WMV/WMA) file type detection parser. When parsing a crafted input where an ASF sub-header has a size field of zero, the parser enters an infinite loop. The payload value becomes negative (-24), causing tokenizer.ignore(payload) to move the read position backwards, so the same sub-header is read repeatedly forever. Any application that uses file-type to detect the type of untrusted/attacker-controlled input is affected. An attacker can stall the Node.js event loop with a 55-byte payload. Fixed in version 21.3.1.

Impact

This vulnerability can cause denial of service by stalling the Node.js event loop, effectively freezing applications that rely on the vulnerable file-type library for file type detection. This can degrade service availability, disrupt processing pipelines, and potentially cause cascading failures in systems that depend on timely file processing. Organizations that accept or process untrusted file inputs—such as web services, file upload handlers, media processing platforms, or security scanners—are at risk. The attack requires minimal payload size and no authentication, increasing the likelihood of exploitation in exposed environments. While the impact is limited to availability and does not compromise data confidentiality or integrity, the resulting service disruption can affect user experience, operational continuity, and potentially lead to resource exhaustion or denial of service conditions in larger scale attacks.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 10 Mar 2026, 21:29 UTC

WeaknessesCWE-835

Technical details

References

Community reviews

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