9.8

CVE-2026-92238: mozilla thunderbird HTTP Request/Response Smuggling

CVSS: 9.8v3.1CriticalAnalyzed
AliasesUBUNTU-CVE-2026-92238DEBIAN-CVE-2026-92238
Published 15-09-2026Last modified 22-09-2026
Open JSON

Vulnerability summary

CVE-2026-92238 is a critical (CVSS 9.8) HTTP Request/Response Smuggling vulnerability in mozilla thunderbird. EPSS estimates a 0.54% chance of exploitation in the next 30 days, higher than 44.2% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.8/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.54%
0%100%
Low · +0.36 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 13 · Related 2
MGASA-2026-0449OPENSUSE-SU-2026:11827-1RHSA-2026:70642RHSA-2026:73130RHSA-2026:73971RHSA-2026:81392

Timeline

  1. 15-09-2026
    PublishedVulnerability first disclosed.
  2. 22-09-2026
    Last modifiedVulnerability information updated.

Description

A maliciously constructed mail header could lead to multiple fields being parsed as one, or potential memory safety violations. This vulnerability was fixed in Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.54%

Chance of exploitation in the next 30 days

Percentile

44%

Versus all other CVEs

30-day change

+0.36 pp

From 0.18% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.54%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Ubuntu8 products
  • mozjs102All versions (No fix recorded)
  • mozjs115All versions (No fix recorded)
  • mozjs38All versions (No fix recorded)
  • mozjs52All versions (No fix recorded)
  • mozjs68All versions (No fix recorded)
Debian1 product
  • thunderbird< 1:140.16.0esr-1~deb12u1 | < 1:140.16.0esr-1~deb13u1 | < 1:153.3.0esr-1
Mozilla1 product
  • thunderbird< 140.16.0 | ≥ 141.0, < 153.3.0 | ≥ 154.0, < 156.0

3 vendors · 10 products

References

7 links