vulnerability / NVI-00017758 / Revision 2
wetty vulnerable to DOM XSS via file-download filename
GitHub lists this reviewed advisory for wetty. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
0.444%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.38726. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
wetty
source listed< 3.0.4
### 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 ```typescript // 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 co
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-p26j-h7wj-r568 ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- CVE-2026-49864 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.