Junrar: RarVM VM_JMP maxOpCount bypass causes infinite CPU loop during RAR4 extraction

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-97370: 0.40% estimated exploitation activity in the next 30 days; percentile 34.53 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Junrar's RAR virtual machine can be forced into a deterministic infinite loop while extracting a crafted RAR4 archive. The RarVM.ExecuteCode loop is intended to be bounded by maxOpCount, but jump instructions can bypass this limit when setIP() is called with a target instruction pointer greater than or equal to codeSize. An unauthenticated attacker who can provide a RAR archive to an application using Junrar.extract() can cause the extraction thread to spin forever, consuming CPU and blocking the process. The issue is a denial of service vulnerability, not remote code execution. Details The root cause is in src/main/java/com/github/junrar/unpack/vm/RarVM.java. setIP() returns early when the target IP is outside the prepared VM program: When ip = codeSize, this branch: - does not update IP; - does not decrement maxOpCount; - returns true, so callers treat it as success. The VMJMP handler and the other jump-like handlers discard the return value of setIP() and immediately…

Published by the source

15 Oct 2026, 20:09 UTC

Last modified by the source

15 Oct 2026, 20:30 UTC

Source last checked

26 Oct 2026, 16:58 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-h9h9-2rmf-rvhp

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-h9h9-2rmf-rvhp

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# Patch Next advisory brief: CVE-2026-97370

Advisory: Junrar: RarVM VM_JMP maxOpCount bypass causes infinite CPU loop during RAR4 extraction
IDs: CVE-2026-97370, GHSA-h9h9-2rmf-rvhp
Record: https://patchnext.com/advisories/cve-2026-97370 (revision 2, source checked 26 Oct 2026, 16:58 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: com.github.junrar:junrar 7.6.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven com.github.junrar:junrar: affected <= 7.6.0; fixed in 7.6.1

## Suggested inspection (read-only)
- Maven com.github.junrar:junrar: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on com.github.junrar:junrar.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-h9h9-2rmf-rvhp (OSV record GHSA-h9h9-2rmf-rvhp lists affected ranges: Maven com.github.junrar:junrar >=0 <7.6.1 (fixed))
- Verified: https://github.com/advisories/GHSA-h9h9-2rmf-rvhp (GitHub-reviewed advisory GHSA-h9h9-2rmf-rvhp lists affected ranges: Maven com.github.junrar:junrar >=0 <=7.6.0)

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