GraphQL-core: Denial of service via comment tokens bypassing the parser's max_tokens limit

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-75508: 0.57% estimated exploitation activity in the next 30 days; percentile 47.38 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The parser's maxtokens limit — the documented defence against oversized GraphQL documents — did not count comment tokens. A document padded with comments could therefore pass a maxtokens check of any size while still allocating one Token object per comment, all of which stay reachable for the lifetime of the parsed document. A 38 MB comment-padded payload allocated roughly 92 MB of additional resident memory with maxtokens=5 in force. Details Lexer.lookahead() reads tokens one at a time and skips over comments, returning only the first non-comment token. Each skipped comment is nevertheless fully tokenized, allocated as a Token object, and linked into the persistent token list via token.next / token.prev — the chain that powers source-location reporting, and which is retained as long as the document is. Parser.advancelexer() incremented the token counter only for the tokens the lexer actually returned. Comments were therefore invisible to the accounting, and maxtokens bounded…

Published by the source

22 Oct 2026, 16:27 UTC

Last modified by the source

22 Oct 2026, 16:45 UTC

Source last checked

26 Oct 2026, 13:55 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-r77w-qph3-7vf8

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-r77w-qph3-7vf8

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-r77w-qph3-7vf8

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# Patch Next advisory brief: CVE-2026-75508

Advisory: GraphQL-core: Denial of service via comment tokens bypassing the parser's max_tokens limit
IDs: CVE-2026-75508, GHSA-r77w-qph3-7vf8
Record: https://patchnext.com/advisories/cve-2026-75508 (revision 3, source checked 26 Oct 2026, 13:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: graphql-core 3.3.0rc1, 3.2.12. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI graphql-core: affected >= 3.2.3, < 3.2.12; >= 3.3.0a3, < 3.3.0rc1; fixed in 3.2.12, 3.3.0rc1

## Suggested inspection (read-only)
- `python -m pip show graphql-core`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on graphql-core.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-r77w-qph3-7vf8 (GitHub-reviewed advisory GHSA-r77w-qph3-7vf8 lists affected ranges: PyPI graphql-core >=3.2.3 =3.3.0a3 <3.3.0rc1)
- Verified: https://osv.dev/vulnerability/GHSA-r77w-qph3-7vf8 (OSV record GHSA-r77w-qph3-7vf8 lists affected ranges: PyPI graphql-core >=3.2.3 =3.3.0a3 <3.3.0rc1 (fixed))

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