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CVE-2026-59873: Isaacs Tar Allocation Without Limits (CVSS 9.2)

CVE-2026-59873 is a critical severity allocation without limits in Isaacs Tar with a CVSS score of 9.2. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Last updated: Jul 10, 2026

Quick answer

Direct answer

CVE-2026-59873 is a critical severity allocation without limits in Isaacs Tar with a CVSS score of 9.2. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Risk scores

CVSS base score
9.2CRITICAL
EPSS probability
0.58%
Higher than 47 percent of all CVEs
CISA KEV
Not listed
CVSS metricWhat it means
Attack vector (AV:N)Network: reachable remotely
Attack complexity (AC:L)Low complexity
Attack requirements (AT:N)No attack requirements
Privileges required (PR:N)No privileges required
User interaction (UI:N)No user interaction
Confidentiality (VC:N)No confidentiality impact
Integrity (VI:N)No integrity impact
Availability (VA:H)High availability impact

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

About Isaacs Tar

CVE-2026-59873 affects Isaacs Tar, a product from Isaacs. Before acting, confirm where Isaacs Tar runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.

What the flaw is

In plain terms: node-tar is a tar archive manipulation library for Node.js. Prior to 7.5.19, node-tar does not enforce hard upper bounds on total decompressed data, entry counts, or decompression ratio in extraction and parsing paths such as src/extract.ts, allowing a small crafted gzip bomb to exhaust disk space and CPU. This issue is fixed in version 7.5.19.

The weakness class is Allocation Without Limits. Resources are allocated without a cap.

Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Affected versions and timeline

FieldDetail
ProductIsaacs Tar
Affected versionsTar before 7.5.19
PublishedJul 8, 2026
Last modifiedJul 10, 2026
Added to CISA KEVNot listed
Assigning CNAsecurity-advisories@github.com

How to detect it

  • Inventory every instance of Isaacs Tar and record the running version against the affected range above.
  • Check external attack surface scans for internet facing instances of the component.
  • Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
  • Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.

How to fix it

  • Apply the fixed version of Isaacs Tar named in the vendor advisory.
  • If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
  • Rescan after the change to prove the exposure is gone, then close the ticket.

CTEM action plan

CTEM stageWhat to do for this CVE
ScopeAdd every business service that depends on Isaacs Tar to the current CTEM cycle.
DiscoverFind all instances, including shadow and cloud deployments, and record versions and exposure.
PrioritizeRank using EPSS and CVSS together with asset exposure and business impact.
ValidateConfirm the flaw is reachable and exploitable in your environment and that compensating controls work.
MobilizeAssign the fix to the asset owner with a due date matched to the priority, then verify closure.

CWE References

Technical References

Frequently asked questions

CVE-2026-59873 is a critical severity allocation without limits in Isaacs Tar with a CVSS score of 9.2. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

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