Several buffer-growth sites in libmime performed size arithmetic in 32-bit types without overflow checks. On a sufficiently large message the growth guard could fail open, or the buffer could be reallocated smaller than required, and a subsequent memcpy would then write attacker-controlled data across adjacent heap allocations. This vulnerability was fixed in Thunderbird 158 and Thunderbird 153.6.
CVE-2026-110247
HIGHPre-NVD 8.48.4
EchelonGraph scoreMEDIUM confidence
“—” beside the score: it is equal to the CVSS score beside it.
Score 8.4 from GitHub Security Advisory (severity: HIGH) published 2026-10-13. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 8.4; sources differ by 0.0.
Triggered by: GitHub Security Advisory CVSS
Sources: CISA-ADP (Vulnrichment) CVSS v3.1, EPSS, GitHub Security Advisory
Also known asEUVD-2026-99207 (ENISA EUVD) · GHSA-6c5g-4xv7-7fmm (GitHub Security Advisories)Source: ENISA EUVD
8.4EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 8.4Exploit: None knownExposed services: Not assessed
The CVE record names the fixed release — apply it.
- CVSS v3
- 8.4
- EG Score
- 8.4HIGHmedium confidence
- EG Risk
- 38EG Risk 38/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity84% × 45%Impact severity (EG Severity): CVSS 8.4 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.2% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: The CVE record names the fixed release. Apply it within your standard update timelines. - EPSS PROB
- 0.2%
- EPSS %ILE
- 8th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (8.4): severity, escalated by confirmed exploitation. This CVE's 8.4 is its impact severity (EG Severity), not escalated.
- EG Severity
- 8.4 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-12). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
The CVE record names the fixed release. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
October 13, 2026
Last Modified
October 27, 2026
Advisory Details (2)
Auto-updated Oct 20, 2026Fix named in the CVE record.
Web page
Security Vulnerabilities fixed in Thunderbird 158 — Mozilla
https://www.mozilla.org/security/advisories/mfsa2026-109/Vendor Advisories for CVE-2026-110247(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(3 across 3 ecosystems)
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| thunderbird | 1:102.11.0-1 ... 1:157.0-1 (248 versions) |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| thunderbird | 1:128.13.0esr-1 ... 1:157.0-1 (103 versions) |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| thunderbird | 1:128.13.0esr-1 ... 1:157.0-1 (103 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 9× in last 7d / 39× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.
- 2026-11-12 21:35 UTCEchelonGraph re-scored
- 2026-11-12 21:35 UTCGHSA enrichmentGHSA-6c5g-4xv7-7fmm · GitHub severity HIGH · GitHub CVSS 8.4
- 2026-11-12 16:32 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-11-11 16:37 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-11-10 16:41 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-11-09 18:12 UTCEchelonGraph re-scored
- 2026-11-09 18:12 UTCGHSA enrichmentGHSA-6c5g-4xv7-7fmm · GitHub severity HIGH · GitHub CVSS 8.4
- 2026-11-09 16:34 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-11-08 16:38 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-11-07 16:38 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-11-06 16:35 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-11-05 16:36 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-11-04 16:34 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-11-03 16:46 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-11-03 06:49 UTCEchelonGraph re-scored
- 2026-11-03 06:49 UTCGHSA enrichmentGHSA-6c5g-4xv7-7fmm · GitHub severity HIGH · GitHub CVSS 8.4
- 2026-11-02 16:43 UTCEPSS rescoreEPSS 0.2% · 7th percentile
- 2026-11-01 16:33 UTCEPSS rescoreEPSS 0.2% · 7th percentile
- 2026-10-31 16:31 UTCEPSS rescoreEPSS 0.2% · 7th percentile
- 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.2% · 7th percentile
- 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.2% · 7th percentile
- 2026-10-28 16:31 UTCEPSS rescoreEPSS 0.2% · 7th percentile
- 2026-10-27 19:26 UTCGHSA enrichmentGHSA-6c5g-4xv7-7fmm · GitHub severity HIGH · GitHub CVSS 8.4
- 2026-10-27 18:30 UTCEchelonGraph re-scored
- 2026-10-27 18:30 UTCGHSA enrichmentGHSA-6c5g-4xv7-7fmm · GitHub severity HIGH · GitHub CVSS 8.4
Show 26 moreShow fewer
- 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-26 16:30 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-25 14:52 UTCEchelonGraph re-scored
- 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.2% · 3rd percentile
- 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.2% · 3rd percentile
- 2026-10-22 16:33 UTCEPSS rescoreEPSS 0.2% · 3rd percentile
- 2026-10-21 17:31 UTCEchelonGraph re-scored
- 2026-10-21 17:31 UTCGHSA enrichmentGHSA-6c5g-4xv7-7fmm · GitHub severity HIGH · GitHub CVSS 8.4
- 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.2% · 3rd percentile
- 2026-10-21 13:57 UTCEchelonGraph re-scored
- 2026-10-21 13:56 UTCGHSA enrichmentGHSA-6c5g-4xv7-7fmm · GitHub severity HIGH · GitHub CVSS 8.4
- 2026-10-20 18:27 UTCGHSA enrichmentGHSA-6c5g-4xv7-7fmm
- 2026-10-20 17:22 UTCEchelonGraph re-scoredFirst assessed: 8.4 HIGH
- 2026-10-20 17:22 UTCGHSA enrichmentGHSA-6c5g-4xv7-7fmm
- 2026-10-20 17:21 UTCMITRE cvelistV5CVSS v3 → 8.4 · severity → HIGH
- 2026-10-20 16:32 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-18 05:06 UTCEchelonGraph re-scored
- 2026-10-16 16:40 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.2% · 6th percentile
- 2026-10-13 19:25 UTCNVD update
- 2026-10-13 18:38 UTCEchelonGraph re-scored
- 2026-10-13 18:34 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-110247?
CVE-2026-110247 is a high-severity vulnerability; its CVE record was published on October 13, 2026. Several buffer-growth sites in libmime performed size arithmetic in 32-bit types without overflow checks. On a sufficiently large message the growth guard could fail open, or the buffer could be reallocated smaller than required, and a subsequent memcpy would then write attacker-controlled data…
When was the CVE record for CVE-2026-110247 published?
The CVE record for CVE-2026-110247 was published on October 13, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 27, 2026; the record at its source may have been updated since.
Is CVE-2026-110247 actively exploited?
CVE-2026-110247 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (8th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-110247?
CVE-2026-110247 has a CVSS v3.1 base score of 8.4 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-110247?
The CVE record for CVE-2026-110247 names the fix: "This vulnerability was fixed in Thunderbird 158 and Thunderbird 153.6." The vendor advisories EchelonGraph has for CVE-2026-110247 are linked in the Vendor Advisories panel on this page.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-110247
Is Your Infrastructure Affected by CVE-2026-110247?
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