CVE-2026-92240: mozilla thunderbird Out-of-bounds Read
CVSS: 9.1v3.1CriticalAnalyzed
AliasesUBUNTU-CVE-2026-92240DEBIAN-CVE-2026-92240
Published 15-09-2026Last modified 22-09-2026
Vulnerability summary
CVE-2026-92240 is a critical (CVSS 9.1) Out-of-bounds Read vulnerability in mozilla thunderbird. EPSS estimates a 0.63% chance of exploitation in the next 30 days, higher than 49.1% of scored vulnerabilities.
CVSS score
9.1/10
010
Critical · v3.1 (CVE.org)EPSS score
0.63%
0%100%
Low · +0.41 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 13 · Related 2Timeline
- 15-09-2026PublishedVulnerability first disclosed.
- 22-09-2026Last modifiedVulnerability information updated.
Description
A malicious or compromised IMAP server can trigger an out-of-bounds read in the IMAP response parser by sending an untagged '* ID' response, crashing Thunderbird. The affected parsing path is reachable before authentication. This vulnerability was fixed in Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.
CVSS metrics
4 scores · 4 sources · 1 versionCritical 9.1Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:HSourcesAll 4 agree
- OSV · UbuntuEcosystem advisory · calculated9.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
- OSV · DebianEcosystem advisory · calculated9.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
- NVDNIST9.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
EPSS trend
Probability
0.63%
Chance of exploitation in the next 30 days
Percentile
49%
Versus all other CVEs
30-day change
+0.41 pp
From 0.21% on 20-09-2026
20-09-202620-10-2026
EPSS score0.63%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected 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- www.mozilla.org/security/advisories/mfsa2026-96/Vendor Advisory
