Security readout for executives and security teams
Plain-English summary
This vulnerability lets a low-privileged local user with valid credentials read files they should not be able to access through Cisco AnyConnect's upgrade component. It is not described as remotely exploitable, but it can expose sensitive local data on affected endpoints.
Executive priority
Treat as a moderate endpoint confidentiality issue. Prioritize environments with shared workstations, contractor access, or sensitive local data, but it should not outrank remotely exploitable or actively exploited vulnerabilities.
Technical view
CVE-2021-1258 is an arbitrary file read in Cisco AnyConnect Secure Mobility Client caused by insufficient file permission restrictions. Exploitation requires local access, low privileges, and valid user credentials. CVSS 3.1 is 5.5 with high confidentiality impact and no integrity or availability impact.
Likely exposure
Exposure is limited to systems running affected Cisco AnyConnect Secure Mobility Client versions. The source bundle does not identify specific vulnerable or fixed versions, so teams must verify applicability against Cisco's advisory and local endpoint inventory.
Exploitation context
The bundle does not report CISA KEV listing or active exploitation. The attack requires an authenticated local user and a crafted local CLI interaction with the application, so risk is highest on shared, less trusted, or broadly accessible endpoints.
Researcher notes
The evidence supports local authenticated arbitrary file read only. Affected version details and concrete fixes are not present in the bundle, so validation depends on Cisco advisory review and asset inventory. Do not assume broader Cisco product impact.
Mitigation direction
- Review Cisco's advisory for affected and fixed AnyConnect versions.
- Upgrade or remediate AnyConnect installations according to Cisco guidance.
- Restrict local interactive access to trusted users where possible.
- Remove unused AnyConnect installations from endpoints.
- Review endpoint hardening for protection of sensitive local files.
Validation and detection
- Inventory endpoints with Cisco AnyConnect Secure Mobility Client installed.
- Compare installed versions with Cisco's advisory scope.
- Confirm whether endpoints allow low-privileged local users.
- Check whether vulnerable systems store sensitive local files.
- Verify remediation status after any Cisco-directed update.
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
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CWE-264: 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 lookupFile access behavior lookup
The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-1258 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
- Medium
- CVSS
- 5.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
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:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N1.83.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.5MediumVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- 20210113 Cisco AnyConnect Secure Mobility Client Arbitrary File Read VulnerabilityCVE reference · vendor-advisory, x_refsource_CISCO
- https://kc.mcafee.com/corporate/index?page=content&id=SB10382CVE reference · x_refsource_CONFIRM
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.
Permissions, Privileges, and Access Controls
Permissions, Privileges, and Access Controls represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.