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CVE-2026-110871

HIGH 7.1

Published 2026-10-14 · Last modified 2026-10-20

Nodemailer from 3.0.0 before 10.0.10 contains a denial of service vulnerability in MessageParser.parseHeaders that allows users to exhaust CPU through quadratic header unfolding. Attackers can supply large recipient lists or long headers that fold into tens of thousands of continuation lines, blocking the Node.js event loop during DKIM signing.

ELEVATED IMPACT

Severe if exploited (CVSS 7.1), but no known exploitation and low modeled probability. Patch on a normal cadence.

Exploitation likelihood

0.4%chance of exploitation in 30 days · 32nd percentile

○ In CISA KEV ○ Catalogued PoC

Impact if exploited

7.1CVSS 4.0 · HIGH

  • ConfidentialityNone
  • IntegrityNone
  • AvailabilityHigh

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ⚠Privileges: Requires a low-privilege account
  • ✓User interaction: No user interaction needed
  • ✓Complexity: No special conditions — reliably repeatable
  • ✓Requirements: No special attack requirements

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept

No public PoC is currently catalogued.

Search for new PoCs

Search GitHub now — results may be empty or unverified.

Tracked sources are checked daily for recent CVEs, including PoCs published after the original disclosure. A later release appears after a tracked source lists it and a refresh succeeds.

Data snapshot:

Affected

Vendors Nodemailer

Products Nodemailer

Weakness (CWE)

  • CWE-400: Uncontrolled Resource Consumption

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

References and research data (JSON)

Packages and version ranges

Each advisory describes its own package and affected ranges. A boundary applies to that range; it is not a universal upgrade recommendation.

  • nodemailer npm

    pkg:npm/nodemailer

    SEMVER range
    • Introduced version (included): 3.0.0
    • Fixed boundary (excluded): 10.0.10
    Additional upstream package constraints
    {
  "database": {
    "last_known_affected_version_range": "<= 10.0.9",
    "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-39m8-27wv-hr27/GHSA-39m8-27wv-hr27.json"
  }
}
    GitHub Advisory Database · GHSA-39m8-27wv-hr27 · Updated 2026-10-22T16:15:47.127282008Z

Vendor product assessments

  • rhdh/rhdh-hub-rhel9 as a component of Red Hat Developer Hub · known affected

    Vendor assessment for this product only.

    pkg:oci/rhdh-hub-rhel9@sha256:0f02ae0b8405912741a180af1c290feac2003e69d062bec9c7cd5d13f8732dc9?repository_url=registry.redhat.io/rhdh/rhdh-hub-rhel9

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. The upstream project has released a fixed version (nodemailer 10.0.10); affected Red Hat products are expected to receive the updated dependency through their regular update streams once the deferred updates are delivered.
    • none available: Fix deferred
    Red Hat · CVE-2026-110871 · Updated 2026-10-16T09:47:35+00:00
  • grafana as a component of Red Hat Enterprise Linux 10 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/grafana

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. The upstream project has released a fixed version (nodemailer 10.0.10); affected Red Hat products are expected to receive the updated dependency through their regular update streams once the deferred updates are delivered.
    • none available: Fix deferred
    Red Hat · CVE-2026-110871 · Updated 2026-10-16T09:47:35+00:00
  • grafana-selinux as a component of Red Hat Enterprise Linux 10 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/grafana-selinux

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. The upstream project has released a fixed version (nodemailer 10.0.10); affected Red Hat products are expected to receive the updated dependency through their regular update streams once the deferred updates are delivered.
    • none available: Fix deferred
    Red Hat · CVE-2026-110871 · Updated 2026-10-16T09:47:35+00:00
  • grafana.src as a component of Red Hat Enterprise Linux 10 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/grafana?arch=src

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. The upstream project has released a fixed version (nodemailer 10.0.10); affected Red Hat products are expected to receive the updated dependency through their regular update streams once the deferred updates are delivered.
    • none available: Fix deferred
    Red Hat · CVE-2026-110871 · Updated 2026-10-16T09:47:35+00:00
  • ansible-automation-platform/bootc-automation-portal-rhel9 as a component of Self-service automation portal 2 · known affected

    Vendor assessment for this product only.

    pkg:oci/bootc-automation-portal-rhel9@sha256:8553c734145775879bdfe2befa9f2df1c22c6d7db2f2251401c3cc517a7e0394?repository_url=registry.redhat.io/ansible-automation-platform/bootc-automation-portal-rhel9

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. The upstream project has released a fixed version (nodemailer 10.0.10); affected Red Hat products are expected to receive the updated dependency through their regular update streams once the deferred updates are delivered.
    • none available: Fix deferred
    Red Hat · CVE-2026-110871 · Updated 2026-10-16T09:47:35+00:00
  • grafana12.4.src as a component of Red Hat Hardened Images · known not affected

    Vendor assessment for this product only.

    Reason: component not present

    pkg:rpm/redhat/[email protected]?arch=src

    Red Hat · CVE-2026-110871 · Updated 2026-10-16T09:47:35+00:00
  • grafana13.1.src as a component of Red Hat Hardened Images · known not affected

    Vendor assessment for this product only.

    Reason: component not present

    pkg:rpm/redhat/[email protected]?arch=src

    Red Hat · CVE-2026-110871 · Updated 2026-10-16T09:47:35+00:00
  • grafana13.2.src as a component of Red Hat Hardened Images · known not affected

    Vendor assessment for this product only.

    Reason: component not present

    pkg:rpm/redhat/[email protected]?arch=src

    Red Hat · CVE-2026-110871 · Updated 2026-10-16T09:47:35+00:00

All CVSS metrics

  • HIGH 7.1 v4.0 · CNA Primary
    CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
  • MEDIUM 6.5 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
  • HIGH 7.1 v4.0 · NVD Secondary
    CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/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
  • MEDIUM 6.5 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

References

Exploit-tagged references (not proof of a PoC)

Advisories

Technical & other

Sources: NVD · CVE.org · EPSS