CVE-2026-6878: ByteDance verl grader.py math_equal sandbox

Is it exploited?

Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of 29 Oct 2026. If CISA adds it, this page shows it as known exploited.

How likely is exploitation in the next 30 days?

0.3%

Down from 0.4% on 22 Oct 2026.

EPSS score, percentile 26.7 of all scored records. A probability estimated by FIRST, not a report of exploitation.

CISA's SSVC assessment in the CVE record lists exploitation as poc.

How severe?

6.3 Medium

CVSS v4.0 base score, given by the CNA

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

The CVE record links no vendor advisory, patch or mitigation.

Which versions are affected?

Affected

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6

and 1 more in the table below

Versions by product

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; FIRST EPSS, as of 29 Oct 2026; CVE List, as of 29 Oct 2026. About the data.

What to do

Advisories and patches

The CVE record links no vendor advisory, patch or mitigation.

This summary is based on the CVE record as of 29 Oct 2026. Check the vendor's advisory before you act: affected versions and fixes can change.

Affected products and versions

As listed in the CVE record.

Source: CVE List, as of 29 Oct 2026. About the data.

About this vulnerability

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…

Summary: CVE record, as of 29 Oct 2026.

• CISA has not added CVE-2026-6878 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
• The CVE record was published on 23 Apr 2026.
• The CVE record carries a CVSS v4.0 base score of 6.3 (Medium), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.3% (percentile 26.7), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
• CISA's SSVC assessment in the CVE record: exploitation poc, automatable no, technical impact partial.
• The credits in the CVE record name ZAST.AI as finder.

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; CVE List, as of 29 Oct 2026; FIRST EPSS, as of 29 Oct 2026. About the data.

Description

ByteDance verl grader.py math_equal sandbox

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.

Source: CVE List, as of 29 Oct 2026. About the data.

Timeline