How severe is CVE-2026-49253?

CVE-2026-49253 has a CVSS score of 7.1/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-49253?

CVE-2026-49253 affects the following packages: electerm (npm). Ecosystems affected: npm.

How do I fix CVE-2026-49253?

Update electerm to 3.11.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-49253 is resolved across your whole dependency graph.

How do I detect CVE-2026-49253 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for electerm, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-49253 if there is no patch (or I can't update yet)?

Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Is CVE-2026-49253 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-49253 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-49253?

CVE-2026-49253 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 38th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-49253?

CVE-2026-49253 is classified as Path Traversal (CWE-22). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-49253 published, and has it been updated?

CVE-2026-49253 was published on August 19, 2026 and was last updated on October 29, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

HIGH severity

CVE-2026-49253 — electerm

HIGHFix: electerm/electerm@fde153d

CVE-2026-49253 is a high-severity (CVSS 7.1) Path Traversal vulnerability in electerm. A fix is available for electerm — see the affected versions and patch details below.

electerm: Path Traversal in Zmodem and Trzsz Download Filename Handling

Also known asGHSA-38j7-23hf-9mhc

Published

Aug 19, 2026

Updated

Oct 29, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 3, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-49253.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs38th percentile — riskier than 38% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

0other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

electermnpm

2Kdownloads / week

Description

Impact

A path traversal vulnerability exists in the Zmodem and Trzsz file download handlers in electerm. When receiving files via Zmodem or Trzsz protocols, electerm uses the remote-supplied filename directly in path.join() with the user-selected download directory without sanitization.

A malicious SSH server or remote shell process can send a specially crafted filename such as ../escaped.txt to escape the user-selected download directory and write files to arbitrary locations on the user's filesystem, subject to process permissions.

Attack scenario:

User connects to a malicious SSH server
Attacker initiates a Zmodem or Trzsz file transfer
Attacker supplies a traversal filename (e.g., ../../.bashrc, ../escaped.txt)
User accepts the transfer and selects a download directory
File is written outside the selected directory, potentially overwriting sensitive files

Affected components:

src/app/server/zmodem.js - prepareReceiveFile() at line 736
src/app/server/trzsz.js - getUniqueFilePath() at line 559, openSaveFile() callback, and savedFilePaths mapping

Patches

https://github.com/electerm/electerm/commit/fde153d677a170c5816368f6586647f3af4ef284

Workarounds

If upgrading is not immediately possible, users can mitigate this vulnerability by:

Only connecting to trusted SSH servers
Rejecting or canceling any incoming Zmodem or Trzsz file transfers from untrusted sources
Avoiding the use of Zmodem (sz/rz) and Trzsz (trz/tsz) commands on untrusted servers

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`electerm`	all versions	3.11.11`npm install electerm@3.11.11`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for electerm, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update electerm to 3.11.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-49253 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Frequently Asked Questions

### Impact A path traversal vulnerability exists in the Zmodem and Trzsz file download handlers in electerm. When receiving files via Zmodem or Trzsz protocols, electerm uses the remote-supplied filename directly in `path.join()` with the user-selected download directory without sanitization. A malicious SSH server or remote shell process can send a specially crafted filename such as `../escaped.txt` to escape the user-selected download directory and write files to arbitrary locations on the user's filesystem, subject to process permissions. **Attack scenario:** 1. User connects to a malici