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Fencer Intel
high 7.5

CVE-2026-21729 json

Loki detected_fields query limits results in unbounded memory allocation

published 3mo ago modified 16d ago also EUVD-2026-44862

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 40%
public exploits
0
none known

Summary

Loki queries with large limits can cause large memory allocations which can impact the availability of the service, depending on its deployment strategy.

Patch / fix

  • Grafana Loki v3.7.0
  • loki3.6 hummingbird 1 3.6.17-0.3.hum1
  • loki3.6-canary hummingbird 1 3.6.17-0.3.hum1
  • loki3.6-logcli hummingbird 1 3.6.17-0.3.hum1

red hat advisories RHSA-2026:72570

Is CVE-2026-21729 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-21729 updated cvss 7.5

Loki: Loki: Denial of Service via large limit queries

  • Red Hat Hardened Images loki3.6 3.6.17-0.3.hum1, loki3.6-canary 3.6.17-0.3.hum1, loki3.6-logcli 3.6.17-0.3.hum1
    fixed: vendor fix RHSA-2026:72570

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
3mo ago

Exploit prediction

0.46% chance of exploitation in the next 30 days, higher than 40% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Grafana Loki

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Intel 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.