CVE-2026-49143 json
BrowserStack Runner 0.9.5 Unauthenticated RCE via /_log HTTP Handler
published 2026-06-02 5 mo ago modified 2026-11-08 27 h ago also EUVD-2026-34029 , GHSA-6vr3-7wcx-v5g5
- cvss
- 8.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.8%
- EPSS 0.8% chance of exploitation in 30 days, percentile 56%
- public exploits
- 0
- none known
Summary
BrowserStack Runner through 0.9.5 contains a remote code execution vulnerability in the /_log HTTP handler that allows unauthenticated network-adjacent attackers to execute arbitrary code by submitting crafted JSON request bodies to the handler, which passes user-supplied data to vm.runInNewContext() combined with eval(). Attackers can escape the Node.js vm sandbox by leveraging a host-context Function reference through util.format to access the host process via this.constructor.constructor, achieving full remote code execution on the underlying system without any authentication.
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- total
- Assessed
- 5 mo ago
Exploit prediction
0.80% chance of exploitation in the next 30 days, higher than 56% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/browserstack/browserstack-runner/security/advisories/GHSA-6vr3-7wcx-v5g5 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 8.7 | CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N |
| CNA | 3.1 | 8.8 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| GitHub | 3.1 | 8.8 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| CNA | 4.0 | 8.7 | CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| npm | browserstack-runner | <=0.9.5 |
no fix listed |
Affected products
- browserstack browserstack-runner
Classification
- Weakness
-
- CWE-94 Improper Control of Generation of Code
References
-
github.com
/browserstack/browserstack-runner/security/advisories/GHSA-6vr3-7wcx-v5g5
vendor-advisory, exploit, web
-
vulncheck.com
/advisories/browserstack-runner-unauthenticated-rce-via-log-http-handler
third-party-advisory, web
-
nvd.nist.gov
/vuln/detail/CVE-2026-49143
advisory
-
github.com
/browserstack/browserstack-runner
package
Sources
- CVE List CVE-2026-49143
- GitHub Advisory GHSA-6vr3-7wcx-v5g5
- NVD CVE-2026-49143
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.