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TI-2026-26011 Aliases CVE-2026-33630

Double free in c-ares

Priority MEDIUM 40CWE-415Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Partial Red Hat: 3 fixed, 1 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-415 and the CVSS impact.

Summary

c-ares is an asynchronous resolver library. From ver 1.32.3 until 1.34.7, a use-after-free / double-free in c-ares' query-completion handling. The same flaw — a query's callback being invoked while the query is still linked in the channel's internal lookup structures — is present at multiple points in the resend/finish path (timeout handling, response handling, and query dispatch). If the query, or for ares_getaddrinfo() the owning host_query, is freed as a side effect of that callback, it is then accessed and/or freed a second time. This vulnerability is fixed in ver 1.34.7.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00845 58th percentileScored 2026-11-07
Fix Partial c-ares (c-ares): 1.34.7Red Hat: 2 advisoriesRed Hat: 3 fixed, 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
c-aresc-ares1.32.3 to before 1.34.71.34.7Patch availableCNA
  • c-ares Vendorc-ares Affected 1.32.3 to before 1.34.7 Fixed in 1.34.7 Patch available CNA

Remediation

  • Fix · CNA c-ares (c-ares) Fixed in 1.34.7

Red Hat 2 advisories

  • RHSA-2026:42096 Released 2026-07-20 · Red Hat rating Important
    c-ares security update
    • Red Hat Enterprise Linux AppStream (v. 10) c-ares-devel-1.34.6-2.el10_2
    • Red Hat Enterprise Linux BaseOS (v. 10) c-ares-1.34.6-2.el10_2
  • RHSA-2026:36192 Released 2026-07-07 · Red Hat rating Important
    Red Hat Hardened Images RPMs bug fix and enhancement update
    • Red Hat Hardened Images c-ares-1.34.7-1.hum1@aarch64, c-ares-1.34.7-1.hum1@src, c-ares-1.34.7-1.hum1@x86_64 +2

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux AppStream (v. 10)Fixed RHSA-2026:42096
Red Hat Enterprise Linux BaseOS (v. 10)Fixed RHSA-2026:42096
Red Hat Hardened ImagesFixed RHSA-2026:36192
Not affected: 5 products
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9
  • Red Hat OpenShift Container Platform 4
  • Red Hat OpenShift Container Platform 5

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-33630
  2. 2026-11-04 Affected versions changed · Red Hat

References

Other 5

  • TI-2026-48538 c-ares: Memory-amplification denial of service via unvalidated DNS header record counts CVSS 3.1MEDIUM 5.3
  • TI-2020-14305 Buffer overflow vulnerability in c-ares before 1_16_1 thru 1_17_0 via function… CVSS 3.1MEDIUM 5.9
  • TI-2016-04481 Heap-based buffer overflow in the ares_create_query function in c-ares 1.x before 1.12.0… CVSS 3.1CRITICAL 9.8
  • TI-2023-15371 0-byte UDP payload DoS in c-ares CVSS 3.1HIGH 7.5
  • TI-2026-48536 c-ares: CPU-exhaustion denial of service via unbounded DNS name compression pointer chains CVSS 3.1HIGH 7.5
  • TI-2017-14601 The c-ares function `ares_parse_naptr_reply()`, which is used for parsing NAPTR… CVSS 3.1HIGH 7.5
See all 13 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences