Analyst readout for executives and security teams
Plain-English summary
CVE-2026-12200 is a remotely reachable buffer overflow in Ritlabs TinyWeb Server for Win32 through version 1.94. A malicious Authorization header can crash or potentially compromise the service. Public exploit information is referenced, but the provided sources do not show confirmed active exploitation or a vendor fix.
Executive priority
Treat as a high-priority exposure reduction item for any reachable TinyWeb deployment. Public exploit information and no named vendor fix increase operational risk. Prioritize removing, replacing, or isolating affected services rather than waiting for confirmed exploitation.
Technical view
The issue affects TinyWeb Server’s Header Handler, specifically handling of the Authorization argument in libeay32.dll.html. VulDB describes a stack-based buffer overflow with network attack vector, low complexity, no authentication, and partial confidentiality, integrity, and availability impact. CVSS v2 is 7.5. CWE mappings include CWE-119 and CWE-121.
Likely exposure
Exposure is most relevant where Ritlabs TinyWeb Server 1.94 or earlier runs on Win32 and accepts untrusted HTTP traffic. Internet-facing deployments are higher risk. Internal-only services still matter if reachable by untrusted users, compromised hosts, or shared networks.
Exploitation context
The source bundle states the exploit has been publicly disclosed and may be used, with exploitability marked as proof-of-concept. KEV is false, and no cited source confirms active exploitation in the wild. Vendor contact reportedly received no response.
Researcher notes
Evidence is largely from VulDB and the CVE record. The vulnerable function is described as unknown, and the vendor reportedly did not respond. The public exploit reference should be reviewed defensively, but avoid reproducing it on production systems.
Mitigation direction
- Identify any Ritlabs TinyWeb Server deployments, especially Win32 versions 1.94 and earlier.
- Remove or replace TinyWeb Server where business need is low.
- Restrict network access to trusted clients only.
- Place affected services behind filtering controls where feasible.
- Monitor vendor and CVE sources for official guidance or updates.
Validation and detection
- Inventory hosts for Ritlabs TinyWeb Server and recorded version.
- Confirm whether the service is reachable from the internet or untrusted networks.
- Review web logs for unusual Authorization header activity.
- Check vulnerability scanners for CVE-2026-12200 coverage.
- Document compensating controls if no patch is available.
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-119: 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 lookupCWE-121: 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-2026-12200 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 (2.0)
- Known Exploited
- No
- Published
Vector: AV:N/AC:L/Au:N/C:P/I:P/A:P/E:POC/RL:ND/RC:UR
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
4 official scoresWe 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.
AV:N/AC:L/Au:N/C:P/I:P/A:P/E:POC/RL:ND/RC:UR 10 6.4 VulDB CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:X/RC:R 3.9 3.4 VulDB CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:X/RC:R 3.9 3.4 VulDB CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P — — VulDB Vulnerability scoring details
Base CVSS 4.0 score
6.9 MediumVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
Base CVSS 3.1 score
7.3 HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:X/RC:R
Base CVSS 3.0 score
7.3 HighVector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:X/RC:R
Base CVSS 2.0 score
7.5 HighVector: AV:N/AC:L/Au:N/C:P/I:P/A:P/E:POC/RL:ND/RC:UR
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- Source timeline VulDB
Advisory disclosed
- Source timeline VulDB
VulDB entry created
- CVE reserved CVE Program
The CVE ID was reserved by the assigning CNA.
- Source timeline VulDB
VulDB entry last update
- CVE published CVE Program
The CVE record was published.
- CVE updated CVE Program
The CVE record metadata indicates this as the latest update time.
Source materials
- CVE List V5 source CVE List V5
- VDB-370842 | Ritlabs TinyWeb Server Header libeay32.dll.html stack-based overflow CVE reference, VulDB · vdb-entry, technical-description
- VDB-370842 | CTI Indicators (IOB, IOC, IOA) CVE reference, VulDB · signature, permissions-required
- CVE-2026-12200 | CVE Analysis and Report CVE reference, VulDB · third-party-advisory
- Submit #829894 | RITLabs TinyWeb 1.94 Stack-based Buffer Overflow CVE reference, VulDB · third-party-advisory
- https://nathan2.com/posts/tinyweb/ CVE reference, VulDB · exploit
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 Restriction of Operations within the Bounds of a Memory Buffer
Improper Restriction of Operations within the Bounds of a Memory Buffer represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Stack-based Buffer Overflow
Stack-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.