VulnerabilityPublished 11 Mar 2026

CVE-2026-31988: thejoshwolfe yauzl · Off-by-one Error

Affects thejoshwolfe yauzlSource CVE Database V5

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Not known to be exploited · CVSS 6.9 Medium : upgrade to 3.2.1 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score

6.9Medium

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

EPSS: 0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.2.1

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, 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: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system 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 Vulnerable System 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 Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 11 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 30 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 thejoshwolfe yauzl to 3.2.1.

Affected software

Product	Affected	Fixed in
thejoshwolfeyauzl	Affected >=3.2.0 <3.2.1	Fixed in 3.2.1
npmyauzl`pkg:npm/yauzl`Other threats	Affected =3.2.0	Fixed in–

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 yauzl library to version 3.2.1 or later, where the off-by-one error has been fixed. For applications that cannot upgrade immediately, implement input validation to reject zip files containing suspicious or malformed NTFS extra fields before processing. Employ sandboxing or process isolation techniques to limit the impact of potential crashes caused by malformed files. Incorporate robust error handling around calls to entry.getLastModDate() to gracefully handle exceptions without crashing the entire application. Monitor application logs for ERR_OUT_OF_RANGE exceptions or unusual crashes related to zip file processing. Additionally, consider rate limiting or filtering zip file uploads from untrusted sources to reduce exposure. Regularly review and update dependencies to ensure vulnerabilities are patched promptly. Finally, conduct security testing on file upload features to detect similar parsing issues proactively.

Description

CVE-2026-31988 is an off-by-one vulnerability in the yauzl Node.js library version 3.2.0, specifically in the NTFS extended timestamp extra field parser within the getLastModDate() function. The flaw allows a crafted zip file with a malformed NTFS extra field to cause a denial of service by triggering a process crash via an ERR_OUT_OF_RANGE exception. This occurs because the code reads beyond the buffer boundary due to incorrect loop boundary checks. The vulnerability affects any Node.js application that processes zip uploads and calls entry.getLastModDate() on parsed entries. No authentication or user interaction is required to exploit this remotely.

Impact

The primary impact of this vulnerability is a denial of service condition caused by a process crash in Node.js applications using yauzl 3.2.0 to process zip files. This can disrupt services that rely on zip file uploads, such as web applications, APIs, or automated processing pipelines, potentially leading to downtime or degraded service availability. Since the vulnerability can be triggered remotely without authentication or user interaction, attackers can exploit it to cause repeated crashes, resulting in service interruptions or resource exhaustion. Although the vulnerability does not lead to code execution or data leakage, the denial of service impact can affect business operations, customer trust, and system reliability. Organizations that rely heavily on Node.js applications for file processing, especially those accepting user-uploaded zip files, are at risk. The absence of known exploits reduces immediate threat but does not eliminate the risk of future exploitation. The medium severity rating reflects the moderate impact and ease of exploitation.

References

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