Evidence used
- No CISA KEV confirmation is currently recorded.
- EPSS is 0.18% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-110247High confidence
Integer overflow in libmime buffer growth could lead to heap corruption
Mozilla · Thunderbird
8.4HighCVSS 3.1
Patch only the product branches with a verified fix
Fix availability varies by productHigh technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 175 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:High, unchanged from published severity.unchanged
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict local access and enforce least privilege on affected hosts.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Mozilla Thunderbird and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Remediation availability differs by product scope
Verified remediation exists for at least one product or source, but 175 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Red Hat Product Security: 10 affected or under-investigation product states without a fixed product state in the same current advisory
- SUSE Product Security Team: 165 affected or under-investigation product states without a fixed product state in the same current advisory
Distribution package intelligence
5 package statesRelease-specific package status
Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
| Distribution release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Debian trixietrixie · source | thunderbird | Not affectedDebian marks this release not affected (fixed-version marker 0). | Not published in this feed | Debian Security Tracker ↗Source updated 4 Nov 2026 |
| Debian bookwormbookworm · source | thunderbird | Not affectedDebian marks this release not affected (fixed-version marker 0). | Not published in this feed | Debian Security Tracker ↗Source updated 4 Nov 2026 |
| Debian forkyforky · source | thunderbird | Not affectedDebian marks this release not affected (fixed-version marker 0). | Not published in this feed | Debian Security Tracker ↗Source updated 4 Nov 2026 |
| Debian sidsid · source | thunderbird | Not affectedDebian marks this release not affected (fixed-version marker 0). | Not published in this feed | Debian Security Tracker ↗Source updated 4 Nov 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | thunderbird | Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 4 Nov 2026 |
Direct vendor intelligence
2 currentAuthoritative vendor CSAF and VEX advisories
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
CVE-2026-110247 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitythunderbird: thunderbird: Arbitrary code execution via integer overflow in libmime
The vendor explicitly identifies these products as affected by this CVE.
- thunderbird as a component of Red Hat Enterprise Linux 10
- thunderbird.src as a component of Red Hat Enterprise Linux 10
- thunderbird as a component of Red Hat Enterprise Linux 6
- thunderbird.src as a component of Red Hat Enterprise Linux 6
- thunderbird as a component of Red Hat Enterprise Linux 7
- thunderbird.src as a component of Red Hat Enterprise Linux 7
- thunderbird as a component of Red Hat Enterprise Linux 8
- thunderbird.src as a component of Red Hat Enterprise Linux 8
- thunderbird as a component of Red Hat Enterprise Linux 9
- thunderbird.src as a component of Red Hat Enterprise Linux 9
- Summary
- A flaw was found in Thunderbird. A remote attacker could exploit an integer overflow in the libmime library to achieve arbitrary code execution or cause a Denial of Service (DoS). By sending a sufficiently large email message, an attacker causes buffer size arithmetic to overflow without proper checks. This leads to heap memory corruption as subsequent memory copy operations overwrite adjacent heap allocations with attacker-controlled data.
- Remediation
- Affected
CVE-2026-110247 · CSAF 2.0 · revision 3 · interimSUSE Product Security TeamCVE-2026-110247
The vendor explicitly identifies these products as affected by this CVE.
- MozillaFirefox as component of SUSE Linux Enterprise Desktop 15 SP7
- MozillaFirefox-devel as component of SUSE Linux Enterprise Desktop 15 SP7
- MozillaFirefox-translations-common as component of SUSE Linux Enterprise Desktop 15 SP7
- MozillaFirefox-translations-other as component of SUSE Linux Enterprise Desktop 15 SP7
- MozillaThunderbird as component of SUSE Linux Enterprise Desktop 15 SP7
- MozillaThunderbird-translations-common as component of SUSE Linux Enterprise Desktop 15 SP7
- MozillaThunderbird-translations-other as component of SUSE Linux Enterprise Desktop 15 SP7
- MozillaFirefox as component of SUSE Linux Enterprise High Performance Computing 12 SP5
- MozillaFirefox-devel as component of SUSE Linux Enterprise High Performance Computing 12 SP5
- MozillaFirefox-translations-common as component of SUSE Linux Enterprise High Performance Computing 12 SP5
- MozillaFirefox as component of SUSE Linux Enterprise High Performance Computing 15 SP1
- MozillaFirefox-devel as component of SUSE Linux Enterprise High Performance Computing 15 SP1
- Summary
- 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.
- Remediation
- No remediation text is recorded.
High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 175 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product01
What, why and how
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.
What
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.
Why
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
How
An attacker operating through local access may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
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.
Why
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
How
An attacker operating through local access may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- local access → Integer Overflow or Wraparound → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Local
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-190 ↗
CWE-190: Integer Overflow or Wraparound. The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.- Post-exploitation / living off the land
- The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Fix availability varies by product
- Affected
- thunderbird as a component of Red Hat Enterprise Linux 10
- thunderbird.src as a component of Red Hat Enterprise Linux 10
- thunderbird as a component of Red Hat Enterprise Linux 6
- thunderbird.src as a component of Red Hat Enterprise Linux 6
- thunderbird as a component of Red Hat Enterprise Linux 7
- thunderbird.src as a component of Red Hat Enterprise Linux 7
- thunderbird as a component of Red Hat Enterprise Linux 8
- thunderbird.src as a component of Red Hat Enterprise Linux 8
- thunderbird as a component of Red Hat Enterprise Linux 9
- thunderbird.src as a component of Red Hat Enterprise Linux 9
- Action
- Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
- Workaround
- No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
Official vendor articles2 stored documents
Linked articles are downloaded and versioned as source evidence. A CVE mention or approved update relationship does not, by itself, verify a fix for every product branch.
- Security Vulnerabilities fixed in Thunderbird 153.6 — Mozilla →Original publisher ↗Searchable text snapshot · Captured 3 Nov 2026Security Vulnerabilities fixed in Thunderbird 153.6 Announced October 27, 2026 Impact high Products Thunderbird Fixed in Thunderbird 153.6 Many of these flaws cannot be exploited through email in the Thunderbird product because scripting is disabled when reading mail, however they may pose risks in browser or br
- Security Vulnerabilities fixed in Thunderbird 158 — Mozilla →Original publisher ↗Searchable text snapshot · Captured 29 Oct 2026Security Vulnerabilities fixed in Thunderbird 158 Announced October 13, 2026 Impact high Products Thunderbird Fixed in Thunderbird 158 Many of these flaws cannot be exploited through email in the Thunderbird product because scripting is disabled when reading mail, however they may pose risks in browser or browse
04
Evidence and provenance
Published 13 Oct 2026 · Last source change 27 Oct 2026, 18:27 UTC · CWE-190 · Integer Overflow or Wraparound
CVE recordCVE.org · 5.2
CVSS sourceCISA ADP
EPSS source FIRST · tracked since 2026-10-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-99207
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCISA ADP
NVD statusNVD awaiting enrichment
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- Affected versionsThe structured affected or fixed version information changed.Red Hat Product Security ↗
- Before
- rhel10/thunderbird-flatpak as a component of Red Hat Enterprise Linux 10; thunderbird as a component of Red Hat Enterprise Linux 10; thunderbird.src as a component of Red Hat Enterprise Linux 10; thunderbird as a component of Red Hat Enterprise Linux 6; thunderbird.src as a component of Red Hat Enterprise Linux 6; thunderbird as a component of Red Hat Enterprise Linux 7; thunderbird.src as a component of Red Hat Enterprise Linux 7; thunderbird as a component of Red Hat Enterprise Linux 8; thunderbird.src as a component of Red Hat Enterprise Linux 8; thunderbird as a component of Red Hat Enterprise Linux 9; thunderbird.src as a component of Red Hat Enterprise Linux 9
- After
- thunderbird as a component of Red Hat Enterprise Linux 10; thunderbird.src as a component of Red Hat Enterprise Linux 10; thunderbird as a component of Red Hat Enterprise Linux 6; thunderbird.src as a component of Red Hat Enterprise Linux 6; thunderbird as a component of Red Hat Enterprise Linux 7; thunderbird.src as a component of Red Hat Enterprise Linux 7; thunderbird as a component of Red Hat Enterprise Linux 8; thunderbird.src as a component of Red Hat Enterprise Linux 8; thunderbird as a component of Red Hat Enterprise Linux 9; thunderbird.src as a component of Red Hat Enterprise Linux 9
- BlackTree coverageBlackTree article coverage changed from no BlackTree article to 1 BlackTree article.BlackTree editorial ↗
- Before
- no BlackTree article
- After
- 1 BlackTree article
- Affected versionsThe structured affected or fixed version information changed.Red Hat Product Security ↗
- Before
- thunderbird as a component of Red Hat Enterprise Linux 10; thunderbird.src as a component of Red Hat Enterprise Linux 10; thunderbird as a component of Red Hat Enterprise Linux 8; thunderbird.src as a component of Red Hat Enterprise Linux 8; thunderbird as a component of Red Hat Enterprise Linux 9; thunderbird.src as a component of Red Hat Enterprise Linux 9
- After
- rhel10/thunderbird-flatpak as a component of Red Hat Enterprise Linux 10; thunderbird as a component of Red Hat Enterprise Linux 10; thunderbird.src as a component of Red Hat Enterprise Linux 10; thunderbird as a component of Red Hat Enterprise Linux 6; thunderbird.src as a component of Red Hat Enterprise Linux 6; thunderbird as a component of Red Hat Enterprise Linux 7; thunderbird.src as a component of Red Hat Enterprise Linux 7; thunderbird as a component of Red Hat Enterprise Linux 8; thunderbird.src as a component of Red Hat Enterprise Linux 8; thunderbird as a component of Red Hat Enterprise Linux 9; thunderbird.src as a component of Red Hat Enterprise Linux 9
- Vendor guidanceAuthoritative vendor guidance changed: added remediation: bugzilla.mozilla.org/show_bug.cgi?id=2071621; removed remediation: mozilla.org/mfsa2026-122.CNA ↗
- Before
- remediation: mozilla.org/mfsa2026-122
- After
- remediation: bugzilla.mozilla.org/show_bug.cgi?id=2071621
- Vendor guidanceAuthoritative vendor guidance changed: added remediation: mozilla.org/mfsa2026-122; removed remediation: bugzilla.mozilla.org/show_bug.cgi?id=2071621.CNA ↗
- Before
- remediation: bugzilla.mozilla.org/show_bug.cgi?id=2071621
- After
- remediation: mozilla.org/mfsa2026-122
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- Before
- See the vendor and CVE records for the affected range. · Fixed: Thunderbird: 158 ≤ *
- After
- See the vendor and CVE records for the affected range. · Fixed: Thunderbird: 153.6 ≤ 153.*, 158 ≤ *
- SeveritySeverity changed from Unknown to High.CISA ADP ↗
- Before
- Unknown
- After
- High
- CVSS scoreCVSS score changed from not recorded to 8.4 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).CISA ADP ↗
- Before
- not recorded
- After
- 8.4 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
- ENISA EUVD mappingEUVD-2026-99207 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2026-99207"}
- Vendor guidanceAuthoritative vendor guidance changed: added remediation: bugzilla.mozilla.org/show_bug.cgi?id=2071621; removed patch: mozilla.org/mfsa2026-109; removed remediation: mozilla.org/mfsa2026-109.CNA ↗
- Before
- patch: mozilla.org/mfsa2026-109 · remediation: mozilla.org/mfsa2026-109
- After
- remediation: bugzilla.mozilla.org/show_bug.cgi?id=2071621
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- Before
- See the linked Mozilla advisory for the product-specific affected versions. · Fixed: Thunderbird 158
- After
- See the vendor and CVE records for the affected range. · Fixed: Thunderbird: 158 ≤ *
- SeveritySeverity changed from Medium to Unknown.CVE.org ↗
- Before
- Medium
- After
- Unknown
- Catalogue recordCVE added to the BlackTree catalogue.Authoritative vendor security advisory ↗
CVE published
Fixed release or patch reference recorded
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.