Security readout for executives and security teams
Plain-English summary
CVE-2021-25255 affects Yandex Browser Lite for Android before version 21.1.0. A remote attacker could cause a denial of service, disrupting browser availability. The sources do not indicate data theft, code execution, or active exploitation.
Executive priority
Treat this as a targeted mobile availability risk. Prioritize remediation where Yandex Browser Lite is installed on managed Android devices, especially where browser availability supports business workflows.
Technical view
The CVE describes improper input validation (CWE-20) leading to denial of service in Yandex Browser Lite for Android prior to 21.1.0. CVSS 4.0 is 8.3: network reachable, low complexity, no privileges, user interaction required, with high availability impact.
Likely exposure
Exposure is limited to Android devices running Yandex Browser Lite versions earlier than 21.1.0. Organizations without this app, or already on 21.1.0 or later, are not indicated as exposed by the provided sources.
Exploitation context
The CVE is not listed in KEV, and the provided sources do not report active exploitation. The CVSS vector indicates exploitation requires network access and user interaction, with denial of service as the documented outcome.
Researcher notes
Public detail is sparse. The record provides product, version boundary, CWE-20, CVSS vector, and denial-of-service impact, but no root cause details, exploit technique, proof of concept, or vendor advisory beyond the bug bounty reference.
Mitigation direction
- Update Yandex Browser Lite for Android to version 21.1.0 or later.
- Remove the app where it is not business-required.
- Use MDM or app controls to block outdated versions.
- Monitor Yandex guidance for any additional vendor-specific remediation.
Validation and detection
- Inventory Android devices for Yandex Browser Lite installations.
- Confirm installed versions are 21.1.0 or later.
- Flag any version earlier than 21.1.0 for remediation.
- Document whether the app is approved for enterprise use.
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-20: Exact CWE lookup
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Open ATT&CK lookupCVE-2021-25255 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
- 8.3 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA: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:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
8.3HighVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H
Source materials
- CVE List V5 sourceCVE List V5
- https://yandex.com/bugbounty/i/hall-of-fame-browser/CVE 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.
Improper Input Validation
Improper Input Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.