RHSA-2026:36192
Vulnerability from csaf_redhat - Published: 2026-07-07 10:32 - Updated: 2026-09-03 19:15Summary
Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update
Severity
Important
Notes
Topic: An update for Red Hat Hardened Images RPMs is now available.
Details: This update includes the following RPMs:
c-ares:
* c-ares-1.34.7-1.hum1 (aarch64, x86_64)
* c-ares-devel-1.34.7-1.hum1 (aarch64, x86_64)
* c-ares-1.34.7-1.hum1.src (src)
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
3 products
| Product | Identifier | Version | Remediation |
|---|---|---|---|
| Unresolved product id: Red Hat Hardened Images:c-ares-main@aarch64 | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: Red Hat Hardened Images:c-ares-main@src | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: Red Hat Hardened Images:c-ares-main@x86_64 | — |
Vendor Fix
fix
Workaround
|
Threats
Impact
Important
References
11 references
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"text": "This update includes the following RPMs:\n\nc-ares:\n * c-ares-1.34.7-1.hum1 (aarch64, x86_64)\n * c-ares-devel-1.34.7-1.hum1 (aarch64, x86_64)\n * c-ares-1.34.7-1.hum1.src (src)",
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"vulnerabilities": [
{
"cve": "CVE-2026-33630",
"cwe": {
"id": "CWE-416",
"name": "Use After Free"
},
"discovery_date": "2026-07-07T00:00:00+00:00",
"ids": [
{
"system_name": "Red Hat Bugzilla ID",
"text": "2497686"
}
],
"notes": [
{
"category": "description",
"text": "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.",
"title": "Vulnerability description"
},
{
"category": "summary",
"text": "c-ares: c-ares: Use-after-free / double-free in query-completion handling",
"title": "Vulnerability summary"
},
{
"category": "other",
"text": "A use-after-free / double-free vulnerability was found in c-ares\u0027 query-completion handling. The flaw is remotely exploitable without application cooperation via ares_getaddrinfo() over TCP: a malicious or on-path DNS server can force a specific sequence of responses (FORMERR without OPT record, duplicate query ID response, TCP reset) that causes the internal completion handler to access freed memory. An attacker can force the client onto TCP by setting the truncation (TC) bit in a UDP response.\n\nThe consequence is memory corruption leading to a crash (denial of service).\n\nThis is a broader fix for the pattern previously addressed in CVE-2025-31498. All versions of c-ares prior to 1.34.7 are affected.",
"title": "Statement"
},
{
"category": "general",
"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.",
"title": "CVSS score applicability"
}
],
"product_status": {
"fixed": [
"Red Hat Hardened Images:c-ares-main@aarch64",
"Red Hat Hardened Images:c-ares-main@src",
"Red Hat Hardened Images:c-ares-main@x86_64"
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"category": "self",
"summary": "Canonical URL",
"url": "https://access.redhat.com/security/cve/CVE-2026-33630"
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{
"category": "external",
"summary": "RHBZ#2497686",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2497686"
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{
"category": "external",
"summary": "https://www.cve.org/CVERecord?id=CVE-2026-33630",
"url": "https://www.cve.org/CVERecord?id=CVE-2026-33630"
},
{
"category": "external",
"summary": "https://nvd.nist.gov/vuln/detail/CVE-2026-33630",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33630"
},
{
"category": "external",
"summary": "https://github.com/c-ares/c-ares/commit/1fa3b86a0b8d18fe7b60f3228a01d770feb026bc",
"url": "https://github.com/c-ares/c-ares/commit/1fa3b86a0b8d18fe7b60f3228a01d770feb026bc"
},
{
"category": "external",
"summary": "https://github.com/c-ares/c-ares/commit/d823199b688052dcdc1646f2ab4cb8c16b1c644a",
"url": "https://github.com/c-ares/c-ares/commit/d823199b688052dcdc1646f2ab4cb8c16b1c644a"
}
],
"release_date": "2026-07-07T00:00:00+00:00",
"remediations": [
{
"category": "vendor_fix",
"date": "2026-07-07T10:32:19+00:00",
"details": "For details on how to apply this update, which includes the changes described in this advisory, refer to:\nhttps://images.redhat.com/",
"product_ids": [
"Red Hat Hardened Images:c-ares-main@aarch64",
"Red Hat Hardened Images:c-ares-main@src",
"Red Hat Hardened Images:c-ares-main@x86_64"
],
"restart_required": {
"category": "none"
},
"url": "https://access.redhat.com/errata/RHSA-2026:36192"
},
{
"category": "workaround",
"details": "There is no complete mitigation for the remotely-triggered path. As a partial mitigation, use trusted DNS resolvers reached over a trusted transport (e.g., DNS-over-TLS). Avoid calling ares_cancel() from within a query callback to prevent the application-triggered path. Upgrade to c-ares 1.34.7 or later.",
"product_ids": [
"Red Hat Hardened Images:c-ares-main@aarch64",
"Red Hat Hardened Images:c-ares-main@src",
"Red Hat Hardened Images:c-ares-main@x86_64"
]
}
],
"scores": [
{
"cvss_v3": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 7.5,
"baseSeverity": "HIGH",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"products": [
"Red Hat Hardened Images:c-ares-main@aarch64",
"Red Hat Hardened Images:c-ares-main@src",
"Red Hat Hardened Images:c-ares-main@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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