Cross-Site Scripting (XSS) in wetty (CVE-2026-49864)
Summary
Cross-site scripting in wetty (CVE-2026-49864). Risk of unauthorized operations or information disclosure. Exploitable via cat. Mitigation: upgrade to 3.0.4 or later.
Original description
The description as published by the source.
Summary
The wetty client decodes a base64 filename from the file-download escape sequence and interpolates it raw into a Toastify HTML string (escapeMarkup: false). Any output the victim renders - a cat'd file, a tailed log, an SSH MOTD, a curl response - that contains \x1b[5i...:...\x1b[4i runs script in the wetty origin and types attacker-chosen keystrokes into the victim's SSH session.
Preconditions
- Victim has wetty open with an active SSH session.
- Attacker delivers the file-download escape sequence (
\x1b[5i:\x1b[4i) into output the victim's terminal renders. - Default configuration; no non-default flags required.
Details
// src/client/wetty.ts:37, 46-62
const fileDownloader = new FileDownloader();
// ...
socket.on('data', (data: string) => {
const remainingData = fileDownloader.buffer(data);
// every PTY byte forwarded by the server passes through buffer()
// ...
})
Every byte the server forwards from the PTY passes through FileDownloader.buffer. The buffer scans for the documented file-download markers \x1b[5i (begin) and \x1b[4i (end) - documented in docs/downloading-files.md - and, on a complete match, hands the inner payload to onCompleteFile.
// src/client/wetty/download.ts:9-77
function onCompleteFile(bufferCharacters: string): void {
let fileNameBase64;
let fileCharacters = bufferCharacters;
if (bufferCharacters.includes(':')) {
[fileNameBase64, fileCharacters] = bufferCharac…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-49864 has been found in wetty.
Attackers can target a specific entry point like cat over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade wetty to 3.0.4 or later.
If unsure, ask your IT team or search "wetty CVE-2026-49864" on the vendor's site.
CVE-2026-49864 (wetty) — CWE-79
Attack surface: cat / curl / FileDownloader.buffer / onCompleteFile
Patched: 3.0.4 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Cross-site scripting (XSS) (CWE-79) exists in wetty. Attackers reach the vulnerable code path via cat.
Check the vendor advisory for the affected versions of wetty. Attack surface: cat / curl / FileDownloader.buffer / onCompleteFile.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 3.0.4.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'wetty' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'wetty' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
wettyを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade wetty to 3.0.4ステージング環境で 3.0.4 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- package github.com
- web github.com
- web github.com