Evidence used
- No CISA KEV confirmation is currently recorded.
- The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
- EPSS is 5.77% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2017
CVE-2016-9843High confidence
The crc32_big function in crc32.c in zlib 1.2.8 might allow context-dependent attackers to have unspecified impact via vectors involving big-endian CRC calculation
Unknown · Unknown
Official source article: Red Hat RHSA-2017:1221 ↗. Check the applicable product and release in the original source.
9.8CriticalCVSS 3.1
Within 72 hours
Patch availableCritical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityCritical→Operational priority:Critical, unchanged from published severity.unchanged
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Unknown Unknown 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
13 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 | mariadb | Vendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected. | 10.3.11-r0 | Alpine Security Database ↗Source updated 22 Oct 2026 |
| Alpine v3.22v3.22 · main | mariadb | Vendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected. | 10.3.11-r0 | Alpine Security Database ↗Source updated 21 Oct 2026 |
| Alpine v3.21v3.21 · main | mariadb | Vendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected. | 10.3.11-r0 | Alpine Security Database ↗Source updated 21 Oct 2026 |
| Debian trixietrixie · source | rsync | Vendor fix publishedDebian records a fixed source-package version for this release. | 3.1.3-6 | Debian Security Tracker ↗Source updated 22 Oct 2026 |
| Debian trixietrixie · source | zlib | Vendor fix publishedDebian records a fixed source-package version for this release. | 1:1.2.8.dfsg-3 | Debian Security Tracker ↗Source updated 22 Oct 2026 |
| Debian bookwormbookworm · source | rsync | Vendor fix publishedDebian records a fixed source-package version for this release. | 3.1.3-6 | Debian Security Tracker ↗Source updated 22 Oct 2026 |
| Debian bookwormbookworm · source | zlib | Vendor fix publishedDebian records a fixed source-package version for this release. | 1:1.2.8.dfsg-3 | Debian Security Tracker ↗Source updated 22 Oct 2026 |
| Debian forkyforky · source | rsync | Vendor fix publishedDebian records a fixed source-package version for this release. | 3.1.3-6 | Debian Security Tracker ↗Source updated 22 Oct 2026 |
| Debian forkyforky · source | zlib | Vendor fix publishedDebian records a fixed source-package version for this release. | 1:1.2.8.dfsg-3 | Debian Security Tracker ↗Source updated 22 Oct 2026 |
| Debian sidsid · source | rsync | Vendor fix publishedDebian records a fixed source-package version for this release. | 3.1.3-6 | Debian Security Tracker ↗Source updated 22 Oct 2026 |
| Debian sidsid · source | zlib | Vendor fix publishedDebian records a fixed source-package version for this release. | 1:1.2.8.dfsg-3 | Debian Security Tracker ↗Source updated 22 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | klibc | Vendor fix publishedCanonical reports that a fixed source package version has been published. Repository candidate availability is not checked by BlackTree. | 2.0.13-4ubuntu0.2 | Canonical Ubuntu Security ↗Source updated 21 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 21 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-2016-9843 · CSAF 2.0 · revision 64 · interimSUSE Product Security TeamCVE-2016-9843
The vendor explicitly identifies these products as affected by this CVE.
- SLES 15 SP1 CHOST Images for Amazon EC2
- SLES 15 SP2 CHOST Images for Amazon EC2
- SLES 15 SP4 CHOST Images for Amazon EC2
- SLES 15 SP5 CHOST Images for Amazon EC2
- SLES 15 SP1 CHOST Images for Google
- SLES 15 SP2 CHOST Images for Google
- SLES 15 SP4 CHOST Images for Google
- SLES 15 SP5 CHOST Images for Google
- SLES 15 SP1 CHOST Images for Microsoft Azure
- SLES 15 SP2 CHOST Images for Microsoft Azure
- SLES 15 SP4 CHOST Images for Microsoft Azure
- SLES 15 SP5 CHOST Images for Microsoft Azure
- Summary
- The crc32_big function in crc32.c in zlib 1.2.8 might allow context-dependent attackers to have unspecified impact via vectors involving big-endian CRC calculation.
- Remediation
- To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded.
Patch available01
What, why and how
The crc32_big function in crc32.c in zlib 1.2.8 might allow context-dependent attackers to have unspecified impact via vectors involving big-endian CRC calculation.
What
The crc32_big function in crc32.c in zlib 1.2.8 might allow context-dependent attackers to have unspecified impact via vectors involving big-endian CRC calculation.
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 a network path 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
The crc32_big function in crc32.c in zlib 1.2.8 might allow context-dependent attackers to have unspecified impact via vectors involving big-endian CRC calculation.
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 a network path 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
- a network path → vulnerable operation → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Network
- 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. - CWE not yet assigned
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:N/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.
AVNetworkAttack vector: The vulnerable component can be reached over a network.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
- 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
- Affected
- SLES 15 SP1 CHOST Images for Amazon EC2
- SLES 15 SP2 CHOST Images for Amazon EC2
- SLES 15 SP4 CHOST Images for Amazon EC2
- SLES 15 SP5 CHOST Images for Amazon EC2
- SLES 15 SP1 CHOST Images for Google
- SLES 15 SP2 CHOST Images for Google
- SLES 15 SP4 CHOST Images for Google
- SLES 15 SP5 CHOST Images for Google
- SLES 15 SP1 CHOST Images for Microsoft Azure
- SLES 15 SP2 CHOST Images for Microsoft Azure
- SLES 15 SP4 CHOST Images for Microsoft Azure
- SLES 15 SP5 CHOST Images for Microsoft Azure
- Action
- To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
- Workaround
- No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
Official vendor articles4 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.
- About the security content of iOS 11 - Apple Support →Original publisher ↗Searchable text snapshot · Captured 17 Oct 2026Apple Store Mac iPad iPhone Watch Vision AirPods Home Entertainment Accessories Support 0 + "},{"name":"compact","assetInline":" "}],"analyticsAttributes":[{"name":"data-analytics-title","value":"apple home"}]},{"id":"ad4a2a26eb4836393385e9f6c61b526b4a3cb31409c5ed8730ce7a704dd7132f","name":"store","text":"
- About the security content of tvOS 11 - Apple Support →Original publisher ↗Searchable text snapshot · Captured 17 Oct 2026Apple Store Mac iPad iPhone Watch Vision AirPods Home Entertainment Accessories Support 0 + "},{"name":"compact","assetInline":" "}],"analyticsAttributes":[{"name":"data-analytics-title","value":"apple home"}]},{"id":"ad4a2a26eb4836393385e9f6c61b526b4a3cb31409c5ed8730ce7a704dd7132f","name":"store","text":"
- About the security content of watchOS 4 - Apple Support →Original publisher ↗Searchable text snapshot · Captured 17 Oct 2026Apple Store Mac iPad iPhone Watch Vision AirPods Home Entertainment Accessories Support 0 + "},{"name":"compact","assetInline":" "}],"analyticsAttributes":[{"name":"data-analytics-title","value":"apple home"}]},{"id":"ad4a2a26eb4836393385e9f6c61b526b4a3cb31409c5ed8730ce7a704dd7132f","name":"store","text":"
- About the security content of macOS High Sierra 10.13 - Apple Support →Original publisher ↗Searchable text snapshot · Captured 17 Oct 2026Apple Store Mac iPad iPhone Watch Vision AirPods Home Entertainment Accessories Support 0 + "},{"name":"compact","assetInline":" "}],"analyticsAttributes":[{"name":"data-analytics-title","value":"apple home"}]},{"id":"ad4a2a26eb4836393385e9f6c61b526b4a3cb31409c5ed8730ce7a704dd7132f","name":"store","text":"
04
Evidence and provenance
Published 23 May 2017 · Last source change 6 Aug 2024, 02:59 UTC · CWE not yet assigned
CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source FIRST · tracked since 2026-09-01
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2016-10643
Product sourceVendor CSAF · SUSE Product Security Team
Remediation sourceVendor CSAF · SUSE Product Security Team
CWE sourceUnavailable
NVD statusNVD modified after enrichment
Missing structured fields: CWE classification, affected product. Missing data is not evidence of low risk; review the primary advisory.
Material change intelligence
View recent updates ↗What changed after publication
- Remediation statusRemediation status changed from Awaiting fix to Mitigation available.SUSE Product Security Team ↗
- Before
- Awaiting fix
- After
- Mitigation available
- ENISA EUVD mappingEUVD-2016-10643 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2016-10643"}
- Vendor guidanceAuthoritative vendor guidance changed: removed vendor advisory: access.redhat.com/RHSA-2017:1220; removed vendor advisory: access.redhat.com/RHSA-2017:1221; 12 further removals.CNA ↗
- Before
- vendor advisory: access.redhat.com/RHSA-2017:1220 · vendor advisory: access.redhat.com/RHSA-2017:1221 · vendor advisory: access.redhat.com/RHSA-2017:1222 · 11 more references
- After
- no authoritative guidance recorded
- SeveritySeverity changed from Unknown to Critical.NIST NVD ↗
- Before
- Unknown
- After
- Critical
- CVSS scoreCVSS score changed from not recorded to 9.8 (CVSS 3.1 · NIST NVD · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).NIST NVD ↗
- Before
- not recorded
- After
- 9.8 (CVSS 3.1 · NIST NVD · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
- Catalogue recordCVE added to the BlackTree catalogue.CNA ↗
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.