Evidence used
- No CISA KEV confirmation is currently recorded.
- EPSS is 0.17% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-86139High confidence
In libxml2 before 2.15.4, xmlURIEscapeStr in uri.c has an integer overflow
xmlsoft · libxml2
6.9MediumCVSS 3.1
Patch only the product branches with a verified fix
Fix availability varies by productMedium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority. Verified remediation exists for at least one product or source, but 1 structured product or package state 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 severityMedium→Operational priority:Medium, 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 xmlsoft libxml2 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 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Debian Security Tracker: 1 affected package state with no published fix
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.
Package result overrides the generic status
BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 1 affected package state shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.
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 | libxml2 | Affected, no fix publishedDebian currently tracks this release as open. | Not published in this feed | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian bookwormbookworm · source | libxml2 | Not affectedDebian marks this release not affected (fixed-version marker 0). | Not published in this feed | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian forkyforky · source | libxml2 | Vendor fix publishedDebian records a fixed source-package version for this release. | 2.15.4+dfsg-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian sidsid · source | libxml2 | Vendor fix publishedDebian records a fixed source-package version for this release. | 2.15.4+dfsg-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | libxml2 | 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 5 Oct 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-2026-86139 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitylibxml2: libxml2: Integer overflow in xmlURIEscapeStr may lead to arbitrary code execution
The vendor explicitly identifies these products or versions as containing the fix.
- libxml2-main@aarch64 as a component of Red Hat Hardened Images
- libxml2-main@src as a component of Red Hat Hardened Images
- libxml2-main@x86_64 as a component of Red Hat Hardened Images
- Summary
- A flaw was found in libxml2. An integer overflow vulnerability exists in the `xmlURIEscapeStr` function within `uri.c`. This flaw could potentially lead to memory corruption, allowing an attacker to achieve information disclosure or arbitrary code execution.
- Remediation
- For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority. Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product01
What, why and how
In libxml2 before 2.15.4, xmlURIEscapeStr in uri.c has an integer overflow.
What
In libxml2 before 2.15.4, xmlURIEscapeStr in uri.c has an integer overflow.
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
In libxml2 before 2.15.4, xmlURIEscapeStr in uri.c has an integer overflow.
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
- High: exploitation depends on specific conditions
- 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:H/PR:N/UI:N/S:U/C:H/I:H/A:LCommon 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.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.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.ALowAvailability impact: A successful attack can cause a limited 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
- libxml2: 0 < 2.15.4
- Fixed
- 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.
04
Evidence and provenance
Published 5 Sept 2026 · Last source change 8 Sept 2026, 13:04 UTC · CWE-190 · Integer Overflow or Wraparound
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-09-06
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-71832
Product sourceCNA
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD enriched
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
- libxml2: < 2.15.4 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- After
- libxml2: < 2.15.4 · Fixed: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
- Vendor guidanceAuthoritative vendor guidance changed from remediation: access.redhat.com/CVE-2026-86139 to remediation: access.redhat.com/CVE-2026-86139.Red Hat Product Security ↗
- Before
- remediation: access.redhat.com/CVE-2026-86139
- After
- remediation: access.redhat.com/CVE-2026-86139
- Remediation statusRemediation status changed from Mitigation available to Patch available.Red Hat Product Security ↗
- Before
- Mitigation available
- After
- Patch available
- Affected versionsThe structured affected or fixed version information changed.Red Hat Product Security ↗
- Before
- libxml2.src as a component of Red Hat Hardened Images
- After
- Fixed: libxml2-main@aarch64 as a component of Red Hat Hardened Images; libxml2-main@src as a component of Red Hat Hardened Images; libxml2-main@x86_64 as a component of Red Hat Hardened Images
- Vendor guidanceAuthoritative vendor guidance changed: added patch: github.com/8edbbdb09f24d26a2f900141fddc2b9d014f53b0; added remediation: github.com/8edbbdb09f24d26a2f900141fddc2b9d014f53b0.cve@mitre.org ↗
- Before
- no authoritative guidance recorded
- After
- patch: github.com/8edbbdb09f24d26a2f900141fddc2b9d014f53b0 · remediation: github.com/8edbbdb09f24d26a2f900141fddc2b9d014f53b0
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- Before
- < 2.15.4 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- After
- libxml2: < 2.15.4 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- Remediation statusRemediation status changed from Awaiting fix to Patch available.cve@mitre.org ↗
- Before
- Awaiting fix
- After
- Patch available
- ENISA EUVD mappingEUVD-2026-71832 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2026-71832"}
- Catalogue recordCVE added to the BlackTree catalogue.CNA ↗
CVE published
Fixed release or patch reference recorded
Fixed release recorded from official guidance
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.