Security readout for executives and security teams
Plain-English summary
CVE-2021-37311 is a buffer overflow in fcitx5 5.0.8. A crafted message sent to the application's listening port can crash the service, causing denial of service. The supplied sources do not show data theft, integrity impact, active exploitation, or a confirmed fixed version.
Executive priority
Treat this as a high-priority availability risk for systems using fcitx5 5.0.8, especially if reachable by untrusted users. It does not currently indicate compromise of confidentiality or integrity, and the supplied evidence does not show known active exploitation.
Technical view
The record describes CWE-120 in fcitx5 5.0.8 with CVSS 3.1 score 7.5: AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. The impact is availability only. The source bundle references upstream fcitx5 PR #308 but does not provide enough detail to confirm remediation specifics.
Likely exposure
Exposure is most likely where fcitx5 5.0.8 is installed and its listening port can receive untrusted messages. Internet exposure should be treated as higher urgency, but the supplied sources do not identify affected platforms or packages beyond fcitx5 5.0.8.
Exploitation context
The source bundle and KEV flag do not support active exploitation. The CVSS vector indicates remote, unauthenticated, low-complexity triggering without user interaction, but only denial of service is described. No exploit steps or weaponization details are provided in the sources.
Researcher notes
Evidence is limited to the CVE description, CVSS vector, CWE-120 classification, and references. The affected metadata is incomplete, listing vendor and product as n/a, while the title and description name fcitx5 5.0.8. Confirm downstream package impact before broad scoping.
Mitigation direction
- Inventory systems for fcitx5 5.0.8 installations.
- Restrict access to the application's listening port from untrusted networks.
- Review upstream fcitx5 guidance and PR #308 for fix status.
- Apply vendor or distribution updates when confirmed available.
- Prioritize exposed systems where service availability matters.
Validation and detection
- Confirm installed fcitx5 versions on relevant endpoints and images.
- Identify whether the fcitx5 listening port is enabled and reachable.
- Check network controls limiting access to the listening port.
- Review vendor or distribution advisories for patched package versions.
- Monitor for crashes or service restarts consistent with denial of service.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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-120: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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 lookupCVE-2021-37311 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
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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.
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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://fcitx-im.org/CVE reference
- https://github.com/fcitx/fcitx5/pull/308CVE reference
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.
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.