Evidence used
- No CISA KEV confirmation is currently recorded.
- A structured source references public exploit or proof-of-concept material.
- EPSS is 0.41% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-22184High confidence
zlib <= 1.3.1.2 untgz Global Buffer Overflow in TGZfname()
zlib software · zlib
4.6MediumCVSS 4.0
Patch only the product branches with a verified fix
Fix availability varies by productMedium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 22 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 severityMedium→Operational priority:Medium, unchanged from published severity.unchanged
Compensating controls
- Apply the linked authoritative mitigation while planning the permanent fix.
- Restrict local access and enforce least privilege on affected hosts.
- Increase monitoring for the attack path and post-exploitation behaviour described in the report.
Verification
- Confirm that the asset runs zlib software zlib and falls inside the recorded affected range.
- Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
- 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 22 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Red Hat Product Security: 21 affected or under-investigation product states without a fixed product state in the same current advisory
- Siemens ProductCERT: 1 affected or under-investigation product state without a fixed product state in the same current advisory
Distribution package intelligence
8 package statesRelease-specific package status
Alpine, 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 |
|---|---|---|---|---|
| Alpine v3.23v3.23 · main | zlib | Vendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected. | 1.3.2-r0 | Alpine Security Database ↗Source updated 3 Oct 2026 |
| Alpine v3.22v3.22 · main | zlib | Vendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected. | 1.3.2-r0 | Alpine Security Database ↗Source updated 3 Oct 2026 |
| Alpine v3.21v3.21 · main | zlib | Vendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected. | 1.3.2-r0 | Alpine Security Database ↗Source updated 3 Oct 2026 |
| Debian trixietrixie · source | zlib | Vendor fix publishedDebian records a fixed source-package version for this release. | 1:1.2.6.dfsg-1 | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Debian bookwormbookworm · source | zlib | Vendor fix publishedDebian records a fixed source-package version for this release. | 1:1.2.6.dfsg-1 | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Debian forkyforky · source | zlib | Vendor fix publishedDebian records a fixed source-package version for this release. | 1:1.2.6.dfsg-1 | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Debian sidsid · source | zlib | Vendor fix publishedDebian records a fixed source-package version for this release. | 1:1.2.6.dfsg-1 | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | zsync | 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
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-2026-22184 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityzlib: zlib: Arbitrary code execution via buffer overflow in untgz utility
The vendor explicitly identifies these products as affected by this CVE.
- openshift-logging/elasticsearch-operator-bundle as a component of Logging Subsystem for Red Hat OpenShift
- openshift-logging/elasticsearch-proxy-rhel9 as a component of Logging Subsystem for Red Hat OpenShift
- openshift-logging/elasticsearch-rhel9-operator as a component of Logging Subsystem for Red Hat OpenShift
- openshift-logging/elasticsearch6-rhel9 as a component of Logging Subsystem for Red Hat OpenShift
- openshift-logging/fluentd-rhel9 as a component of Logging Subsystem for Red Hat OpenShift
- openshift-logging/kibana6-rhel8 as a component of Logging Subsystem for Red Hat OpenShift
- openshift-logging/logging-curator5-rhel9 as a component of Logging Subsystem for Red Hat OpenShift
- mingw32-zlib as a component of Red Hat Enterprise Linux 10
- mingw32-zlib-static as a component of Red Hat Enterprise Linux 10
- mingw64-zlib as a component of Red Hat Enterprise Linux 10
- mingw64-zlib-static as a component of Red Hat Enterprise Linux 10
- mingw-zlib.src as a component of Red Hat Enterprise Linux 8
- Summary
- A flaw was found in zlib. A global buffer overflow vulnerability exists in the `untgz` utility, specifically within the `TGZfname()` function. This flaw allows an attacker to provide an archive name longer than 1024 bytes, leading to an out-of-bounds write. This can result in memory corruption, denial of service, and potentially arbitrary code execution on the affected system.
- Remediation
- To mitigate this vulnerability, avoid using the `untgz` utility with untrusted archive names or from untrusted sources. System administrators should ensure that any automated processes or user interactions involving `untgz` validate the length of archive names to prevent triggering the buffer overflow. If the `untgz` utility is not essential for system operation, consider restricting its execution permissions or removing the package that provides it, if applicable.
SSA-470355 · CSAF 2.0 · revision 1 · interimSiemens ProductCERTSSA-470355: Zlib and Foxit Vulnerabilities in CADRA
The vendor explicitly identifies these products as affected by this CVE.
- CADRA
- Summary
- zlib versions up to and including 1.3.1.2 include a global buffer overflow in the untgz utility located under contrib/untgz. The vulnerability is limited to the standalone demonstration utility and does not affect the core zlib compression library. The flaw occurs when a user executes the untgz command with an excessively long archive name supplied via the command line, leading to an out-of-bounds write in a fixed-size global buffer.
- Remediation
- Currently no fix is available
Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 22 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
zlib versions up to and including 1.3.1.2 include a global buffer overflow in the untgz utility located under contrib/untgz. The vulnerability is limited to the standalone demonstration utility and does not affect the core zlib compression library. The flaw occurs when a user executes the untgz command with an excessively long archive name supplied via the command line, leading to an out-of-bounds write in a fixed-size global buffer.
What
zlib versions up to and including 1.3.1.2 include a global buffer overflow in the untgz utility located under contrib/untgz. The vulnerability is limited to the standalone demonstration utility and does not affect the core zlib compression library. The flaw occurs when a user executes the untgz command with an excessively long archive name supplied via the command line, leading to an out-of-bounds write in a fixed-size global buffer.
Why
A bounds error lets data be written beyond the intended memory region, potentially corrupting control data.
How
An attacker operating through local access 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
zlib versions up to and including 1.3.1.2 include a global buffer overflow in the untgz utility located under contrib/untgz. The vulnerability is limited to the standalone demonstration utility and does not affect the core zlib compression library. The flaw occurs when a user executes the untgz command with an excessively long archive name supplied via the command line, leading to an out-of-bounds write in a fixed-size global buffer.
Why
A bounds error lets data be written beyond the intended memory region, potentially corrupting control data.
How
An attacker operating through local access 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 Reference recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.CISA Vulnrichment records proof-of-concept exploitation in its SSVC data. BlackTree has not independently executed or validated exploit material.
- Likely attack path
- local access → Out-of-bounds Write → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Local
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- Active interaction required
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Not a CVSS 4.0 base metric
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-787 ↗
CWE-787: Out-of-bounds Write. The product writes data past the end, or before the beginning, of the intended buffer.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:N/VA:L/SC:N/SI:N/SA:NCommon Vulnerability Scoring System 4.0: 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.ATNoneAttack requirements: No additional deployment or execution condition is required.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIActiveUser interaction: A user must take a deliberate action for exploitation to succeed.VCLowVulnerable-system confidentiality: A successful attack can cause a limited loss.VINoneVulnerable-system integrity: No direct loss is represented by this metric.VALowVulnerable-system availability: A successful attack can cause a limited loss.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.- 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
- openshift-logging/elasticsearch-operator-bundle as a component of Logging Subsystem for Red Hat OpenShift
- openshift-logging/elasticsearch-proxy-rhel9 as a component of Logging Subsystem for Red Hat OpenShift
- openshift-logging/elasticsearch-rhel9-operator as a component of Logging Subsystem for Red Hat OpenShift
- openshift-logging/elasticsearch6-rhel9 as a component of Logging Subsystem for Red Hat OpenShift
- openshift-logging/fluentd-rhel9 as a component of Logging Subsystem for Red Hat OpenShift
- openshift-logging/kibana6-rhel8 as a component of Logging Subsystem for Red Hat OpenShift
- openshift-logging/logging-curator5-rhel9 as a component of Logging Subsystem for Red Hat OpenShift
- mingw32-zlib as a component of Red Hat Enterprise Linux 10
- mingw32-zlib-static as a component of Red Hat Enterprise Linux 10
- mingw64-zlib as a component of Red Hat Enterprise Linux 10
- mingw64-zlib-static as a component of Red Hat Enterprise Linux 10
- mingw-zlib.src as a component of Red Hat Enterprise Linux 8
- mingw32-zlib as a component of Red Hat Enterprise Linux 8
- mingw32-zlib-static as a component of Red Hat Enterprise Linux 8
- mingw64-zlib as a component of Red Hat Enterprise Linux 8
- mingw64-zlib-static as a component of Red Hat Enterprise Linux 8
- mingw-zlib.src as a component of Red Hat Enterprise Linux 9
- mingw32-zlib as a component of Red Hat Enterprise Linux 9
- mingw32-zlib-static as a component of Red Hat Enterprise Linux 9
- mingw64-zlib as a component of Red Hat Enterprise Linux 9
- mingw64-zlib-static 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
- To mitigate this vulnerability, avoid using the `untgz` utility with untrusted archive names or from untrusted sources. System administrators should ensure that any automated processes or user interactions involving `untgz` validate the length of archive names to prevent triggering the buffer overflow. If the `untgz` utility is not essential for system operation, consider restricting its execution permissions or removing the package that provides it, if applicable.
04
Evidence and provenance
Published 7 Jan 2026 · Last source change 1 Sept 2026, 12:04 UTC · CWE-787 · Out-of-bounds Write
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-1173
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD modified after 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.CNA ↗
- Before
- ≤ 1.3.1.2 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- After
- zlib: ≤ 1.3.1.2 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
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.