adm-zip: Memory Allocation with Excessive Size Value
CVE-2026-77301 is a high-severity memory allocation with excessive size value vulnerability in adm-zip from Cthackers, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected adm-zip versions: < 0.6.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.61% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of adm-zip you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA (github.com).
Official description
adm-zip is a JavaScript library for creating and extracting ZIP archives in Node.js. Prior to 0.6.1, getData() in zipEntry.js trusts an entry's central-directory uncompressed size and allocates output memory before validating that value against the actual compressed data and decompression result. A small crafted ZIP can declare a multi-gigabyte uncompressed size, causing Buffer.alloc and decompression handling to commit excessive resident memory before CRC validation reports an error. Applications that read entries from untrusted archives can therefore be terminated by the operating system or suffer service-wide memory exhaustion. This issue is fixed in version 0.6.1.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Memory Allocation with Excessive Size Value
The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated.
How developers prevent this class of flaw
- Perform adequate input validation against any value that influences the amount of memory that is allocated. Define an appropriate strategy for handling requests that exceed the limit, and consider supporting a configuration option so that the administrator can extend the amount of memory to be used if necessary.
- Run your program using system-provided resource limits for memory. This might still cause the program to crash or exit, but the impact to the rest of the system will be minimized.
More Memory Allocation with Excessive Size Value vulnerabilities (CWE-789)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other vulnerabilities in adm-zip
- 7.5 High severity
- 7.1 High severity
- 7.5 High severity
Recent Memory Allocation with Excessive Size Value vulnerabilities
- 7.5 High severity
- 8.6 High severity
- 8.9 High severity
- 7.5 High severity
- 7.5 High severity
- 9.8 Critical severity
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