eml_parser has recursion DoS via nested message/rfc822 attachments

Exploitation

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

CVSS 4.0

6.3 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-44844: 0.40% estimated exploitation activity in the next 30 days; percentile 33.84 (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 EmlParser.getrawbodytext() recurses unconditionally for every nested message/rfc822 attachment without any depth limit. An attacker who can supply a badly crafted EML file with approximately 120 nested message/rfc822 parts triggers an unhandled RecursionError and aborts parsing of the message. A 12 KB EML file is enough to crash a worker. Though this causes the parser to crash, it is an unlikely scenario as the suggested EML that crashes the parser would not pass basic RFC compliance tests. Details The vulnerable function is EmlParser.getrawbodytext() in emlparser/parser.py. For every part of type multipart/, the function iterates over its sub-parts; for every sub-part of type message/rfc822, it calls itself recursively on the inner message: There is no depth parameter and no early-abort. CPython's default sys.recursionlimit is 1000. Each level of message/rfc822 nesting adds approximately 8 frames to the stack (parser code + stdlib headervalueparser calls), so roughly 120…

Published by the source

8 May 2026, 23:12 UTC

Last modified by the source

13 Jul 2026, 16:43 UTC

Source last checked

26 Oct 2026, 13:45 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-g47v-rwmh-r9f8

2. Revision 2 · amended · 24 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-g47v-rwmh-r9f8

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# Patch Next advisory brief: CVE-2026-44844

Advisory: eml_parser has recursion DoS via nested message/rfc822 attachments
IDs: CVE-2026-44844, GHSA-g47v-rwmh-r9f8
Record: https://patchnext.com/advisories/cve-2026-44844 (revision 3, source checked 26 Oct 2026, 13:45 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: eml-parser 3.0.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI eml-parser: affected <= 3.0.0; fixed in 3.0.1

## Suggested inspection (read-only)
- `python -m pip show eml-parser`: prints the installed version. Run with the environment that serves production active.

## 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 eml-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-g47v-rwmh-r9f8 (OSV record GHSA-g47v-rwmh-r9f8 lists affected ranges: PyPI eml-parser >=0 <3.0.1 (fixed))
- Verified: https://github.com/advisories/GHSA-g47v-rwmh-r9f8 (GitHub-reviewed advisory GHSA-g47v-rwmh-r9f8 lists affected ranges: PyPI eml-parser >=0 <=3.0.0)

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