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High, CVSS 7.5amended

zbateson/mail-mime-parser has uncontrolled resource consumption (CPU/memory DoS) parsing untrusted MIME

CVE-2026-61816GHSA-f6v3-2qmr-vfjx

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (zbateson/mail-mime-parser 4.0.2, 3.0.6), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
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-2026-61816: 0.39% estimated exploitation activity in the next 30 days; percentile 33.53 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Impact An uncontrolled resource consumption / algorithmic complexity vulnerability affecting any application that parses untrusted email with this library. Three independent parsing paths are super-linear in cost, so a byte-size cap on the caller side does not bound the work done. A crafted message under 2 MB can consume seconds of CPU or hundreds of megabytes to multiple gigabytes of memory (leading to an out-of-memory kill), enabling denial of service. The parse is lazy, but the cost is paid on the first getAllParts() or content read. Details 1. Deep multipart nesting is O(depth²). MimeParserService::findContentBoundary() tests each content line against the current part and every ancestor via the recursive ParserMimePartProxy::setEndBoundaryFound(), so a nesting depth of D costs 1 + 2 + … + D comparisons. A ~600 KB message nested ~10,000 deep does not finish parsing in a minute. 2. Many sibling parts is O(n²). PartChildrenContainer::add() appends each child with…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-f6v3-2qmr-vfjx

  2. Revision 1 · created ·

    Published from osv record GHSA-f6v3-2qmr-vfjx

Agent brief

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# Patch Next advisory brief: CVE-2026-61816

Advisory: zbateson/mail-mime-parser has uncontrolled resource consumption (CPU/memory DoS) parsing untrusted MIME
IDs: CVE-2026-61816, GHSA-f6v3-2qmr-vfjx
Record: https://patchnext.com/advisories/cve-2026-61816 (revision 2, source checked 26 Oct 2026, 14:53 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: zbateson/mail-mime-parser 4.0.2, 3.0.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist zbateson/mail-mime-parser: affected >= 2.0.0, < 3.0.6; >= 4.0.0, < 4.0.2; fixed in 3.0.6, 4.0.2

## Suggested inspection (read-only)
- Packagist zbateson/mail-mime-parser: 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 zbateson/mail-mime-parser.
- 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-f6v3-2qmr-vfjx (OSV record GHSA-f6v3-2qmr-vfjx lists affected ranges: Packagist zbateson/mail-mime-parser >=2.0.0 =4.0.0 <4.0.2 (fixed))
- Verified: https://github.com/advisories/GHSA-f6v3-2qmr-vfjx (GitHub-reviewed advisory GHSA-f6v3-2qmr-vfjx lists affected ranges: Packagist zbateson/mail-mime-parser >=2.0.0 =4.0.0 <4.0.2)

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