TS-2026-015
Vulnerability from tailscale - Published: Mon, 26 Oct 2026 00:00:00 GMT
Description: Memory exhaustion in Tailscale SSH session handling could lead to denial of service.
What happened?
Tailscale SSH provides a secure shell server integrated into tailscaled. An issue in the embedded SSH server's session handling allowed authenticated peers to cause unbounded memory growth in the tailscaled process. This occurred through continuous window-change messages and environment variable appends within a session. These allocations persisted even after the peer disconnected.
Tailscale now bounds the memory used for session handling and releases it when the peer disconnects.
This vulnerability is fixed in Tailscale version 1.104.4 or newer.
What was the impact?
An attacker could exhaust available memory on the host, leading to an out-of-memory (OOM) kill of the tailscaled process. Because tailscaled is central to all node networking state, such a crash disrupts every Tailscale connection on the node.
Who was affected?
This issue affects nodes running the Tailscale SSH server. An authenticated SSH session permitted by policy is required to trigger the condition.
What do I need to do?
If you use Tailscale SSH, upgrade to Tailscale version 1.104.4 or newer.
Show details on source website{
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"summary": "\u003cp\u003e\u003cstrong\u003e\u003cem\u003eDescription\u003c/em\u003e\u003c/strong\u003e: Memory exhaustion in Tailscale SSH session handling could lead to denial of service.\u003c/p\u003e\n\u003ch4\u003eWhat happened?\u003c/h4\u003e\n\u003cp\u003e\u003ca href=\"https://tailscale.com/docs/features/tailscale-ssh\"\u003eTailscale SSH\u003c/a\u003e provides a secure shell server integrated into \u003ccode\u003etailscaled\u003c/code\u003e. An issue in the embedded SSH server\u0027s session handling allowed authenticated peers to cause unbounded memory growth in the \u003ccode\u003etailscaled\u003c/code\u003e process. This occurred through continuous window-change messages and environment variable appends within a session. These allocations persisted even after the peer disconnected.\u003c/p\u003e\n\u003cp\u003eTailscale now bounds the memory used for session handling and releases it when the peer disconnects.\u003c/p\u003e\n\u003cp\u003eThis vulnerability is fixed in Tailscale version 1.104.4 or newer.\u003c/p\u003e\n\u003ch4\u003eWhat was the impact?\u003c/h4\u003e\n\u003cp\u003eAn attacker could exhaust available memory on the host, leading to an out-of-memory (OOM) kill of the \u003ccode\u003etailscaled\u003c/code\u003e process. Because \u003ccode\u003etailscaled\u003c/code\u003e is central to all node networking state, such a crash disrupts every Tailscale connection on the node.\u003c/p\u003e\n\u003ch4\u003eWho was affected?\u003c/h4\u003e\n\u003cp\u003eThis issue affects nodes running the Tailscale SSH server. An authenticated SSH session permitted by policy is required to trigger the condition.\u003c/p\u003e\n\u003ch4\u003eWhat do I need to do?\u003c/h4\u003e\n\u003cp\u003eIf you use Tailscale SSH, upgrade to Tailscale version 1.104.4 or newer.\u003c/p\u003e",
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"value": "\u003cp\u003e\u003cstrong\u003e\u003cem\u003eDescription\u003c/em\u003e\u003c/strong\u003e: Memory exhaustion in Tailscale SSH session handling could lead to denial of service.\u003c/p\u003e\n\u003ch4\u003eWhat happened?\u003c/h4\u003e\n\u003cp\u003e\u003ca href=\"https://tailscale.com/docs/features/tailscale-ssh\"\u003eTailscale SSH\u003c/a\u003e provides a secure shell server integrated into \u003ccode\u003etailscaled\u003c/code\u003e. An issue in the embedded SSH server\u0027s session handling allowed authenticated peers to cause unbounded memory growth in the \u003ccode\u003etailscaled\u003c/code\u003e process. This occurred through continuous window-change messages and environment variable appends within a session. These allocations persisted even after the peer disconnected.\u003c/p\u003e\n\u003cp\u003eTailscale now bounds the memory used for session handling and releases it when the peer disconnects.\u003c/p\u003e\n\u003cp\u003eThis vulnerability is fixed in Tailscale version 1.104.4 or newer.\u003c/p\u003e\n\u003ch4\u003eWhat was the impact?\u003c/h4\u003e\n\u003cp\u003eAn attacker could exhaust available memory on the host, leading to an out-of-memory (OOM) kill of the \u003ccode\u003etailscaled\u003c/code\u003e process. Because \u003ccode\u003etailscaled\u003c/code\u003e is central to all node networking state, such a crash disrupts every Tailscale connection on the node.\u003c/p\u003e\n\u003ch4\u003eWho was affected?\u003c/h4\u003e\n\u003cp\u003eThis issue affects nodes running the Tailscale SSH server. An authenticated SSH session permitted by policy is required to trigger the condition.\u003c/p\u003e\n\u003ch4\u003eWhat do I need to do?\u003c/h4\u003e\n\u003cp\u003eIf you use Tailscale SSH, upgrade to Tailscale version 1.104.4 or newer.\u003c/p\u003e"
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Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
How durations are calculated
Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.
Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.