RHSA-2026:35453
Vulnerability from csaf_redhat - Published: 2026-07-03 13:43 - Updated: 2026-07-17 16:49Summary
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:
haproxy:
* haproxy-3.0.25-0.1.hum1 (aarch64, x86_64)
* haproxy-3.0.25-0.1.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 HAProxy. A malicious FastCGI (Fast Common Gateway Interface) backend can exploit an integer overflow vulnerability in the fcgi_conn structure's drl field. This occurs when specific contentLength and paddingLength values cause the drl field to wrap to zero, leading to incorrect record consumption. This desynchronizes the FCGI framing parser, potentially resulting in response smuggling, request routing errors, or memory safety issues.
7.5 (High)
Affected products
Fixed
3 products
| Product | Identifier | Version | Remediation |
|---|---|---|---|
| Unresolved product id: Red Hat Hardened Images:haproxy-main@aarch64 | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: Red Hat Hardened Images:haproxy-main@src | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: Red Hat Hardened Images:haproxy-main@x86_64 | — |
Vendor Fix
fix
Workaround
|
Threats
Impact
Important
A flaw was found in HAProxy. An attacker can trigger HPACK dynamic table insertions under memory pressure, leading to a null pointer dereference in the hpack_dht_insert() function. This can cause HAProxy worker processes to crash, resulting in a denial of service (DoS).
7.5 (High)
Affected products
Fixed
3 products
| Product | Identifier | Version | Remediation |
|---|---|---|---|
| Unresolved product id: Red Hat Hardened Images:haproxy-main@aarch64 | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: Red Hat Hardened Images:haproxy-main@src | — |
Vendor Fix
fix
Workaround
|
|
| Unresolved product id: Red Hat Hardened Images:haproxy-main@x86_64 | — |
Vendor Fix
fix
Workaround
|
Threats
Impact
Important
References
18 references
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"text": "This update includes the following RPMs:\n\nhaproxy:\n * haproxy-3.0.25-0.1.hum1 (aarch64, x86_64)\n * haproxy-3.0.25-0.1.hum1.src (src)",
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"vulnerabilities": [
{
"cve": "CVE-2026-55203",
"cwe": {
"id": "CWE-190",
"name": "Integer Overflow or Wraparound"
},
"discovery_date": "2026-06-18T17:02:00.523729+00:00",
"ids": [
{
"system_name": "Red Hat Bugzilla ID",
"text": "2490522"
}
],
"notes": [
{
"category": "description",
"text": "A flaw was found in HAProxy. A malicious FastCGI (Fast Common Gateway Interface) backend can exploit an integer overflow vulnerability in the fcgi_conn structure\u0027s drl field. This occurs when specific contentLength and paddingLength values cause the drl field to wrap to zero, leading to incorrect record consumption. This desynchronizes the FCGI framing parser, potentially resulting in response smuggling, request routing errors, or memory safety issues.",
"title": "Vulnerability description"
},
{
"category": "summary",
"text": "haproxy: HAProxy: Response smuggling due to integer overflow in FastCGI record length handling",
"title": "Vulnerability summary"
},
{
"category": "other",
"text": "Conditions for Exploitation: Successful exploitation requires a specific configuration where HAProxy is actively utilizing a FastCGI backend. Crucially, an attacker must already have control over this backend server to supply the maliciously crafted responses. \n\nThis requirement significantly restricts the attack vector, as it relies on an unlikely configuration or an already compromised backend, rather than a typical remote attack initiated by a client against a default frontend server.\n\nImpact Limitations: Although the vulnerability can cause the FastCGI framing parser to desynchronize\u2014potentially leading to response smuggling, request routing errors, or memory safety issues\u2014the threat is contained entirely to environments that process traffic from untrusted or compromised backend servers.",
"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:haproxy-main@aarch64",
"Red Hat Hardened Images:haproxy-main@src",
"Red Hat Hardened Images:haproxy-main@x86_64"
]
},
"references": [
{
"category": "self",
"summary": "Canonical URL",
"url": "https://access.redhat.com/security/cve/CVE-2026-55203"
},
{
"category": "external",
"summary": "RHBZ#2490522",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2490522"
},
{
"category": "external",
"summary": "https://www.cve.org/CVERecord?id=CVE-2026-55203",
"url": "https://www.cve.org/CVERecord?id=CVE-2026-55203"
},
{
"category": "external",
"summary": "https://nvd.nist.gov/vuln/detail/CVE-2026-55203",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-55203"
},
{
"category": "external",
"summary": "https://github.com/haproxy/haproxy/commit/5985276735777634d8c85f1d73bb7764aab0d6dd",
"url": "https://github.com/haproxy/haproxy/commit/5985276735777634d8c85f1d73bb7764aab0d6dd"
},
{
"category": "external",
"summary": "https://www.vulncheck.com/advisories/haproxy-integer-overflow-in-fcgi-demux-record-length-field",
"url": "https://www.vulncheck.com/advisories/haproxy-integer-overflow-in-fcgi-demux-record-length-field"
}
],
"release_date": "2026-06-18T16:05:20.100000+00:00",
"remediations": [
{
"category": "vendor_fix",
"date": "2026-07-03T13:43:49+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:haproxy-main@aarch64",
"Red Hat Hardened Images:haproxy-main@src",
"Red Hat Hardened Images:haproxy-main@x86_64"
],
"restart_required": {
"category": "none"
},
"url": "https://access.redhat.com/errata/RHSA-2026:35453"
},
{
"category": "workaround",
"details": "To mitigate this issue, restrict access to HAProxy instances that utilize FastCGI to trusted FastCGI backends only. If FastCGI is not required, consider disabling its use in HAProxy configurations to eliminate the attack vector. Ensure that all FastCGI backends are secured and not susceptible to compromise. If the HAProxy service is reloaded or restarted after configuration changes, ensure proper validation of the new configuration.",
"product_ids": [
"Red Hat Hardened Images:haproxy-main@aarch64",
"Red Hat Hardened Images:haproxy-main@src",
"Red Hat Hardened Images:haproxy-main@x86_64"
]
}
],
"scores": [
{
"cvss_v3": {
"attackComplexity": "HIGH",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 7.5,
"baseSeverity": "HIGH",
"confidentialityImpact": "LOW",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "CHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N",
"version": "3.1"
},
"products": [
"Red Hat Hardened Images:haproxy-main@aarch64",
"Red Hat Hardened Images:haproxy-main@src",
"Red Hat Hardened Images:haproxy-main@x86_64"
]
}
],
"threats": [
{
"category": "impact",
"details": "Important"
}
],
"title": "haproxy: HAProxy: Response smuggling due to integer overflow in FastCGI record length handling"
},
{
"cve": "CVE-2026-55204",
"cwe": {
"id": "CWE-476",
"name": "NULL Pointer Dereference"
},
"discovery_date": "2026-06-18T17:01:46.312939+00:00",
"ids": [
{
"system_name": "Red Hat Bugzilla ID",
"text": "2490518"
}
],
"notes": [
{
"category": "description",
"text": "A flaw was found in HAProxy. An attacker can trigger HPACK dynamic table insertions under memory pressure, leading to a null pointer dereference in the hpack_dht_insert() function. This can cause HAProxy worker processes to crash, resulting in a denial of service (DoS).",
"title": "Vulnerability description"
},
{
"category": "summary",
"text": "haproxy: HAProxy: Denial of Service via HPACK dynamic table insertions",
"title": "Vulnerability summary"
},
{
"category": "other",
"text": "This Important flaw in HAProxy can lead to a denial of service. An unauthenticated remote attacker could exploit a null pointer dereference by triggering HPACK dynamic table insertions under memory pressure, causing HAProxy worker processes to crash. This impacts the availability of services relying on HAProxy as a load balancer or proxy.",
"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:haproxy-main@aarch64",
"Red Hat Hardened Images:haproxy-main@src",
"Red Hat Hardened Images:haproxy-main@x86_64"
]
},
"references": [
{
"category": "self",
"summary": "Canonical URL",
"url": "https://access.redhat.com/security/cve/CVE-2026-55204"
},
{
"category": "external",
"summary": "RHBZ#2490518",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2490518"
},
{
"category": "external",
"summary": "https://www.cve.org/CVERecord?id=CVE-2026-55204",
"url": "https://www.cve.org/CVERecord?id=CVE-2026-55204"
},
{
"category": "external",
"summary": "https://nvd.nist.gov/vuln/detail/CVE-2026-55204",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-55204"
},
{
"category": "external",
"summary": "https://github.com/haproxy/haproxy/commit/9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513",
"url": "https://github.com/haproxy/haproxy/commit/9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513"
},
{
"category": "external",
"summary": "https://www.vulncheck.com/advisories/haproxy-null-pointer-dereference-in-hpack-dht-insert-function",
"url": "https://www.vulncheck.com/advisories/haproxy-null-pointer-dereference-in-hpack-dht-insert-function"
}
],
"release_date": "2026-06-18T16:05:52.058000+00:00",
"remediations": [
{
"category": "vendor_fix",
"date": "2026-07-03T13:43:49+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:haproxy-main@aarch64",
"Red Hat Hardened Images:haproxy-main@src",
"Red Hat Hardened Images:haproxy-main@x86_64"
],
"restart_required": {
"category": "none"
},
"url": "https://access.redhat.com/errata/RHSA-2026:35453"
},
{
"category": "workaround",
"details": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.",
"product_ids": [
"Red Hat Hardened Images:haproxy-main@aarch64",
"Red Hat Hardened Images:haproxy-main@src",
"Red Hat Hardened Images:haproxy-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:haproxy-main@aarch64",
"Red Hat Hardened Images:haproxy-main@src",
"Red Hat Hardened Images:haproxy-main@x86_64"
]
}
],
"threats": [
{
"category": "impact",
"details": "Important"
}
],
"title": "haproxy: HAProxy: Denial of Service via HPACK dynamic table insertions"
}
]
}
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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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