Analyst readout for executives and security teams
Plain-English summary
Logback has a low-severity weakness in a restricted deserialization path. If an attacker can send crafted serialized data to Logback's SimpleSocketServer or SimpleSSLSocketServer, they may bypass intended class restrictions. Sources state no practical remote-code-execution or significant privilege-escalation path has been identified.
Executive priority
Treat this as routine patch management unless the affected logging socket servers are exposed to untrusted networks. The public evidence describes a security-control bypass, not a proven high-impact compromise path.
Technical view
CVE-2026-9828 affects logback-core through 1.5.32 inclusive, specifically HardenedObjectInputStream used with SimpleSocketServer and SimpleSSLSocketServer. The whitelist can be bypassed enough to instantiate unblocked java.lang and java.util classes. The issue is CWE-502 with CVSS 4.0 score 2.9 and high attack complexity.
Likely exposure
Exposure is likely limited to Java applications using vulnerable logback-core versions and accepting serialized logging events through SimpleSocketServer or SimpleSSLSocketServer. Applications that do not expose these components to untrusted input are less likely to be meaningfully exposed.
Exploitation context
The CVE is not listed as KEV, and the provided sources do not report active exploitation. Exploitation requires the attacker to influence serialized data sent to the affected socket server components, and the reported impact remains restricted.
Researcher notes
The key research question is reachability of SimpleSocketServer or SimpleSSLSocketServer and whether untrusted serialized input can reach HardenedObjectInputStream. The source explicitly says no practical RCE or significant privilege escalation has been identified, so avoid overstating impact.
Mitigation direction
- Inventory applications using logback-core through 1.5.32 inclusive.
- Review the Logback 1.5.33 vendor guidance and update accordingly.
- Disable SimpleSocketServer or SimpleSSLSocketServer where not required.
- Restrict network access to logging socket servers to trusted sources only.
- Monitor QOS.CH advisories for any updated mitigation details.
Validation and detection
- Check dependency manifests for logback-core versions through 1.5.32.
- Identify whether SimpleSocketServer or SimpleSSLSocketServer is configured or reachable.
- Confirm logging socket endpoints are not exposed to untrusted networks.
- Review deployment firewalls and service bindings for affected components.
- Document compensating controls if immediate update is not possible.
Public sources used
Based on public source material and reviewed before publication.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-502: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-9828 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Low
- CVSS
- 2.9 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:P/RE:L/U:Green
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:P/RE:L/U:Green — — NCSC.ch Vulnerability scoring details
Base CVSS 4.0 score
2.9 LowVector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:P/RE:L/U:Green
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reserved CVE Program
The CVE ID was reserved by the assigning CNA.
- CVE published CVE Program
The CVE record was published.
- CVE updated CVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 source CVE List V5
- https://logback.qos.ch/news.html#1.5.33 CVE reference, NCSC.ch
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Deserialization of Untrusted Data
Deserialization of Untrusted Data represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.