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Advisory record · GHSA-f2hq-32vh-53cc

postal-mime: Quadratic CPU consumption when decoding a header of many joinable RFC 2047 base64 encoded words

CVSS 7.5 High

Published by the GitHub Advisory Database at 23 Oct 2026, 21:54 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
postal-mimenpm>=3.0.0, <4.0.84.0.8
Identifiers
GHSA-f2hq-32vh-53cc
Weakness (CWE)
CWE-400 · CWE-407
Tags
Published
23 Oct 2026
Updated
23 Oct 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Versions 3.0.0 through 4.0.7 of the postal-mime npm package are affected by quadratic CPU consumption when decoding a header containing a long run of joinable RFC 2047 base64 encoded words. An attacker who can send a crafted mail message to an application that parses it with postal-mime can block the event loop for a long time, causing denial of service; the source reports no confidentiality or integrity impact. Upgrade to version 4.0.8, which fixes the issue, or lower maxHeadersSize from its default as a workaround.

Written 31 Oct 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
7.5 High 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H GitHub Advisory Database
  • CISA KEV Not listed.
  • EPSS No score.

Timeline

  1. 31 Oct 2026, 13:33 UTC First seen by agentprime
  2. 31 Oct 2026, 13:33 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.