# CVE-2026-118175: Content of other messages could be included when replying to a crafted message

Status: published. Published: 2026-10-27. Updated: 2026-11-04.

When replying to, forwarding, or editing a crafted email message as new, Thunderbird could embed parts of a different message stored in the same folder into the message being composed, without showing a blocked content warning. If the user sent the message, the content of the other message was disclosed to the recipients. This vulnerability was fixed in Thunderbird 159 and Thunderbird 153.6.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Mozilla / Thunderbird: ≥ 153.6; ≤ 153.* (unaffected, rpm); ≥ 159; ≤ * (unaffected, rpm). Source: CNA: mozilla

## Severity and prioritization

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N; source: ADP: CISA-ADP

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N; source: NVD: 134c704f-9b21-4f2e-91b3-4a467353bcc0

- CISA KEV: No listing in collected sources

- EPSS: 0.18% as of 2026-11-04; percentile 7.58%

- SSVC: exploitation none; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-200

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://bugzilla.mozilla.org/show_bug.cgi?id=2081720 (CNA: mozilla)

- https://www.mozilla.org/security/advisories/mfsa2026-121/ (CNA: mozilla)

- https://www.mozilla.org/security/advisories/mfsa2026-122/ (CNA: mozilla)

- https://bugzilla.mozilla.org/show_bug.cgi?id=2081720 (security@mozilla.org)

- https://www.mozilla.org/security/advisories/mfsa2026-121/ (security@mozilla.org)

- https://www.mozilla.org/security/advisories/mfsa2026-122/ (security@mozilla.org)

## Provenance

- CNA: mozilla: https://www.cve.org/CVERecord?id=CVE-2026-118175; retrieved 2026-11-04; source updated 2026-11-04

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-118175; retrieved 2026-11-04; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-118175; retrieved 2026-11-04; source updated Not reported

Revision: 586a979a8390cbfda982d42f13264cef167d5a9c04c2562093e84199588923dd

Canonical: https://y2.dev/cve/CVE-2026-118175

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.