RHSA-2026:42096
Vulnerability from csaf_redhat - Published: 2026-07-20 19:48 - Updated: 2026-09-03 19:15Summary
Red Hat Security Advisory: c-ares security update
Severity
Important
Notes
Topic: An update for c-ares is now available for Red Hat Enterprise Linux 10.
Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.
Details: The c-ares C library defines asynchronous DNS (Domain Name System) requests and provides name resolving API.
Security Fix(es):
* c-ares: c-ares: Use-after-free / double-free in query-completion handling (CVE-2026-33630)
For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.
Terms of Use: This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Red Hat Inc. and provide a link to the original.
A flaw was found in c-ares. A use-after-free / double-free vulnerability exists in the query-completion handling path, where a query callback is invoked while the query is still linked in internal lookup structures. A remote attacker can exploit this via ares_getaddrinfo() over TCP by sending crafted DNS responses that force an EDNS-downgrade retry followed by a connection reset, causing the internal completion handler to access freed memory. This leads to memory corruption and a crash (denial of service), with potential for further impact depending on the allocator and build configuration.
7.5 (High)
Affected products
Fixed
25 products
| Product | Identifier | Version | Remediation |
|---|---|---|---|
| Unresolved product id: AppStream-10.2.Z:c-ares-debuginfo-0:1.34.6-2.el10_2.aarch64 | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: AppStream-10.2.Z:c-ares-debuginfo-0:1.34.6-2.el10_2.ppc64le | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: AppStream-10.2.Z:c-ares-debuginfo-0:1.34.6-2.el10_2.s390x | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: AppStream-10.2.Z:c-ares-debuginfo-0:1.34.6-2.el10_2.x86_64 | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: AppStream-10.2.Z:c-ares-debugsource-0:1.34.6-2.el10_2.aarch64 | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: AppStream-10.2.Z:c-ares-debugsource-0:1.34.6-2.el10_2.ppc64le | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: AppStream-10.2.Z:c-ares-debugsource-0:1.34.6-2.el10_2.s390x | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: AppStream-10.2.Z:c-ares-debugsource-0:1.34.6-2.el10_2.x86_64 | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: AppStream-10.2.Z:c-ares-devel-0:1.34.6-2.el10_2.aarch64 | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: AppStream-10.2.Z:c-ares-devel-0:1.34.6-2.el10_2.ppc64le | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: AppStream-10.2.Z:c-ares-devel-0:1.34.6-2.el10_2.s390x | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: AppStream-10.2.Z:c-ares-devel-0:1.34.6-2.el10_2.x86_64 | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: BaseOS-10.2.Z:c-ares-0:1.34.6-2.el10_2.aarch64 | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: BaseOS-10.2.Z:c-ares-0:1.34.6-2.el10_2.ppc64le | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: BaseOS-10.2.Z:c-ares-0:1.34.6-2.el10_2.s390x | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: BaseOS-10.2.Z:c-ares-0:1.34.6-2.el10_2.src | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: BaseOS-10.2.Z:c-ares-0:1.34.6-2.el10_2.x86_64 | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: BaseOS-10.2.Z:c-ares-debuginfo-0:1.34.6-2.el10_2.aarch64 | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: BaseOS-10.2.Z:c-ares-debuginfo-0:1.34.6-2.el10_2.ppc64le | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: BaseOS-10.2.Z:c-ares-debuginfo-0:1.34.6-2.el10_2.s390x | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: BaseOS-10.2.Z:c-ares-debuginfo-0:1.34.6-2.el10_2.x86_64 | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: BaseOS-10.2.Z:c-ares-debugsource-0:1.34.6-2.el10_2.aarch64 | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: BaseOS-10.2.Z:c-ares-debugsource-0:1.34.6-2.el10_2.ppc64le | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: BaseOS-10.2.Z:c-ares-debugsource-0:1.34.6-2.el10_2.s390x | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: BaseOS-10.2.Z:c-ares-debugsource-0:1.34.6-2.el10_2.x86_64 | — |
Vendor Fix
fix
Workaround
|
Threats
Impact
Important
References
10 references
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"title": "Statement"
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"text": "The CVSS score(s) listed for this vulnerability do not reflect the associated product\u0027s status, and are included for informational purposes to better understand the severity of this vulnerability.",
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"BaseOS-10.2.Z:c-ares-debuginfo-0:1.34.6-2.el10_2.s390x",
"BaseOS-10.2.Z:c-ares-debuginfo-0:1.34.6-2.el10_2.x86_64",
"BaseOS-10.2.Z:c-ares-debugsource-0:1.34.6-2.el10_2.aarch64",
"BaseOS-10.2.Z:c-ares-debugsource-0:1.34.6-2.el10_2.ppc64le",
"BaseOS-10.2.Z:c-ares-debugsource-0:1.34.6-2.el10_2.s390x",
"BaseOS-10.2.Z:c-ares-debugsource-0:1.34.6-2.el10_2.x86_64"
]
}
],
"threats": [
{
"category": "impact",
"details": "Important"
}
],
"title": "c-ares: c-ares: Use-after-free / double-free in query-completion handling"
}
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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