VulnerabilityPublished 2 Jul 2026

CVE-2026-49253: Electerm Has Path Traversal

Affects electermSource GCVE Database

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Authoritative record:CVE-2026-49253· High 7.1

Not known to be exploited · CVSS 7.1 High : upgrade to 3.11.11 soon.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 3.1 base score

7.1High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.4% chance of exploitation in 30 days – higher than 38% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.11.11

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: None
Integrity: High
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 19 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade electerm to 3.11.11.

Affected software

Product	Affected	Fixed in
npmelecterm	Affected <3.11.11	Fixed in 3.11.11

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AI-suggested

A patch fixing this vulnerability is available in electerm version 3.11.11 and later; users should upgrade to this version or newer. If immediate upgrading is not possible, users should only connect to trusted SSH servers, reject or cancel any incoming Zmodem or Trzsz file transfers from untrusted sources, and avoid using Zmodem and Trzsz commands on untrusted servers.

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:** 1. User connects to a malicious SSH server 2. Attacker initiates a Zmodem or Trzsz file transfer 3. Attacker supplies a traversal filename (e.g., `../../.bashrc`, `../escaped.txt`) 4. User accepts the transfer and selects a download directory 5. 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: 1. Only connecting to trusted SSH servers 2. Rejecting or canceling any incoming Zmodem or Trzsz file transfers from untrusted sources 3. Avoiding the use of Zmodem (`sz`/`rz`) and Trzsz (`trz`/`tsz`) commands on untrusted servers

Impact

An attacker controlling a malicious SSH server or remote shell can exploit this vulnerability by sending specially crafted filenames during Zmodem or Trzsz file transfers. This can cause files to be written outside the user-selected download directory, potentially overwriting sensitive files on the user's filesystem. The impact includes integrity loss of local files and possible disruption of user environments. The vulnerability requires user interaction (accepting a file transfer) and does not affect confidentiality or availability directly.

Summary

electerm versions before 3.11.11 contain a path traversal vulnerability in the Zmodem and Trzsz file download handlers. The vulnerability arises because electerm uses the remote-supplied filename directly in path.join() with the user-selected download directory without sanitization. This allows a malicious SSH server or remote shell to send filenames containing traversal sequences (e.g., '../escaped.txt'), causing files to be written outside the intended directory. The affected code components include prepareReceiveFile() in src/app/server/zmodem.js and getUniqueFilePath() and openSaveFile() in src/app/server/trzsz.js. A patch has been committed to fix this issue.

CWE-22Improper Limitation of a Pathname to a Restricted Directory (Path Traversal) (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #6OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks…
Implementation · Input Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174).
OWASP Cheat Sheets
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V12.3.1 (opens in a new tab)
Attack patterns
Path Traversal (opens in a new tab)
Using Slashes and URL Encoding Combined to Bypass Validation Logic (opens in a new tab)
Manipulating Web Input to File System Calls (opens in a new tab)
Using Escaped Slashes in Alternate Encoding (opens in a new tab)
Using Slashes in Alternate Encoding (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 2 Jul 2026, 23:13 UTC

WeaknessesCWE-22

Technical details

References

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