Evidence used
- No CISA KEV confirmation is currently recorded.
- EPSS is 0.14% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-118023High confidence
Sandbox escape due to use-after-free in the Graphics: WebRender component
Mozilla · Firefox
…UnscoredAssess manually
Needs assessment
Patch availableNo CVSS base score is available from the CNA, CISA ADP or NIST. Absence of a score is not evidence of low risk; review the vendor advisory, affected exposure and exploit evidence.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityUnscored→Operational priority:Needs assessment, manual assessment needed.unscored
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 Firefox 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.
Distribution package intelligence
3 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 sidsid · source | firefox | Vendor fix publishedDebian records a fixed source-package version for this release. | 159.0-1 | Debian Security Tracker ↗Source updated 4 Nov 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | mozjs102 | 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 |
| Ubuntu 24.04 LTSnoble · standard archive | mozjs115 | 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
1 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-2026-118023 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityfirefox: thunderbird: Sandbox escape due to use-after-free in the Graphics: WebRender component
The vendor explicitly states that these products are not affected by this CVE.
- firefox as a component of Red Hat Enterprise Linux 10
- firefox.src as a component of Red Hat Enterprise Linux 10
- rhel10/firefox-flatpak as a component of Red Hat Enterprise Linux 10
- 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
- firefox as a component of Red Hat Enterprise Linux 6
- firefox.src as a component of Red Hat Enterprise Linux 6
- thunderbird as a component of Red Hat Enterprise Linux 6
- thunderbird.src as a component of Red Hat Enterprise Linux 6
- firefox as a component of Red Hat Enterprise Linux 7
- firefox.src as a component of Red Hat Enterprise Linux 7
- Summary
- A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue: Sandbox escape due to use-after-free in the Graphics: WebRender component
- Remediation
- No remediation text is recorded.
No CVSS base score is available from the CNA, CISA ADP or NIST. Absence of a score is not evidence of low risk; review the vendor advisory, affected exposure and exploit evidence.
Patch available01
What, why and how
Sandbox escape due to use-after-free in the Graphics: WebRender component. This vulnerability was fixed in Firefox 159 and Thunderbird 159.
What
Sandbox escape due to use-after-free in the Graphics: WebRender component. This vulnerability was fixed in Firefox 159 and Thunderbird 159.
Why
The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.
How
An attacker operating through the affected interface may attempt exploitation when the stated preconditions are met. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
Sandbox escape due to use-after-free in the Graphics: WebRender component. This vulnerability was fixed in Firefox 159 and Thunderbird 159.
Why
The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.
How
An attacker operating through the affected interface may attempt exploitation when the stated preconditions are met. 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
- the affected interface → vulnerable operation → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Unspecified
- Privileges required
- Not stated in the selected CVSS metric
- User interaction
- Not stated in the selected CVSS metric
- Attack complexity
- Not stated in the selected CVSS metric
- Security boundary
- Not stated in the selected CVSS metric
- Weakness
?
CWE means Common Weakness Enumeration. - CWE not yet assigned
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. Not available from the selected scoring authority.- Post-exploitation / living off the land
- No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
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. - Patch available
- Action
- Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
- 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 Firefox 159 — Mozilla →Original publisher ↗Searchable text snapshot · Captured 3 Nov 2026Security Vulnerabilities fixed in Firefox 159 Announced October 27, 2026 Impact high Products Firefox Fixed in Firefox 159 Note : We have changed how we publish advisories. We no longer roll all internally identified memory safety vulnerabilities into a single CVE and are now issuing an advisory for every indivi
- Security Vulnerabilities fixed in Thunderbird 159 — Mozilla →Original publisher ↗Searchable text snapshot · Captured 3 Nov 2026Security Vulnerabilities fixed in Thunderbird 159 Announced October 27, 2026 Impact high Products Thunderbird Fixed in Thunderbird 159 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 27 Oct 2026 · Last source change 27 Oct 2026, 18:18 UTC · CWE not yet assigned
CVE recordCVE.org · 5.2
CVSS sourceUnavailable
EPSS source FIRST · tracked since 2026-10-28
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-110921
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceUnavailable
NVD statusNVD not scheduled
Missing structured fields: CVSS base score, affected versions, CWE classification. Missing data is not evidence of low risk; review the primary advisory.
Material change intelligence
View recent updates ↗What changed after publication
- BlackTree coverageBlackTree article coverage changed from no BlackTree article to 1 BlackTree article.BlackTree editorial ↗
- Before
- no BlackTree article
- After
- 1 BlackTree article
- ENISA EUVD mappingEUVD-2026-110921 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2026-110921"}
- Vendor guidanceAuthoritative vendor guidance changed: added remediation: bugzilla.mozilla.org/show_bug.cgi?id=2079499; removed remediation: mozilla.org/mfsa2026-121.CNA ↗
- Before
- remediation: mozilla.org/mfsa2026-121
- After
- remediation: bugzilla.mozilla.org/show_bug.cgi?id=2079499
- Vendor guidanceAuthoritative vendor guidance changed: added remediation: mozilla.org/mfsa2026-121; removed remediation: bugzilla.mozilla.org/show_bug.cgi?id=2079499.CNA ↗
- Before
- remediation: bugzilla.mozilla.org/show_bug.cgi?id=2079499
- After
- remediation: mozilla.org/mfsa2026-121
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- Before
- See the vendor and CVE records for the affected range. · Fixed: Firefox: 159 ≤ *
- After
- See the vendor and CVE records for the affected range. · Fixed: Firefox: 159 ≤ *; Thunderbird: 159 ≤ *
- Catalogue recordCVE added to the BlackTree catalogue.CNA ↗
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.