CVE-2026-54556 (GCVE-0-2026-54556)
Vulnerability from cvelistv5
Published
2026-08-26 14:10
Modified
2026-08-29 02:38
Severity ?
VLAI Severity ?
EPSS score ?
CWE
- CWE-409 - Improper Handling of Highly Compressed Data (Data Amplification)
Summary
Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, an unauthenticated HTTP/2 peer can cause an out-of-memory denial of service in the Ember backend with HTTP/2 enabled. The Hpack wrapper in ember-core/shared/src/main/scala/org/http4s/ember/core/h2/Hpack.scala concatenates HEADERS and CONTINUATION frame fragments and decodes them into a single List, but maxHeaderSize accounting does not include indexed headers or HPACK per-header overhead. A small compressed header block can therefore expand into a much larger decoded representation that remains in memory for processing. Servers exposed to untrusted HTTP/2 traffic and clients directed to an untrusted HTTP/2 server are affected, and concurrent malicious connections can exhaust the process heap. This issue is fixed in versions 0.23.35 and 1.0.0-M47.
References
| URL | Tags | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
||||||||||||||
Impacted products
| Vendor | Product | Version | |||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| http4s | http4s |
Version: < 0.23.35 Version: >= 1.0.0-M1, < 1.0.0-M46 |
|||||||||||||||||
|
|||||||||||||||||||
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-54556",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-08-29T02:38:20.242464Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-08-29T02:38:44.725Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"product": "http4s",
"vendor": "http4s",
"versions": [
{
"status": "affected",
"version": "\u003c 0.23.35"
},
{
"status": "affected",
"version": "\u003e= 1.0.0-M1, \u003c 1.0.0-M46"
}
]
},
{
"product": "http4s-ember-core_2.12",
"vendor": "org.http4s",
"versions": [
{
"status": "affected",
"version": "\u003c 0.23.35"
}
]
},
{
"product": "http4s-ember-core_2.13",
"vendor": "org.http4s",
"versions": [
{
"status": "affected",
"version": "\u003e= 1.0.0-M1, \u003c 1.0.0-M46"
},
{
"status": "affected",
"version": "\u003c 0.23.35"
}
]
},
{
"product": "http4s-ember-core_3",
"vendor": "org.http4s",
"versions": [
{
"status": "affected",
"version": "\u003e= 1.0.0-M1, \u003c 1.0.0-M46"
},
{
"status": "affected",
"version": "\u003c 0.23.35"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, an unauthenticated HTTP/2 peer can cause an out-of-memory denial of service in the Ember backend with HTTP/2 enabled. The Hpack wrapper in ember-core/shared/src/main/scala/org/http4s/ember/core/h2/Hpack.scala concatenates HEADERS and CONTINUATION frame fragments and decodes them into a single List, but maxHeaderSize accounting does not include indexed headers or HPACK per-header overhead. A small compressed header block can therefore expand into a much larger decoded representation that remains in memory for processing. Servers exposed to untrusted HTTP/2 traffic and clients directed to an untrusted HTTP/2 server are affected, and concurrent malicious connections can exhaust the process heap. This issue is fixed in versions 0.23.35 and 1.0.0-M47."
}
],
"metrics": [
{
"cvssV4_0": {
"attackComplexity": "LOW",
"attackRequirements": "PRESENT",
"attackVector": "NETWORK",
"baseScore": 8.2,
"baseSeverity": "HIGH",
"privilegesRequired": "NONE",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "HIGH",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "NONE"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-409",
"description": "CWE-409: Improper Handling of Highly Compressed Data (Data Amplification)",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-26T14:10:22.349Z",
"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"shortName": "GitHub_M"
},
"references": [
{
"name": "https://github.com/http4s/http4s/security/advisories/GHSA-vmm3-xgcx-67hm",
"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/http4s/http4s/security/advisories/GHSA-vmm3-xgcx-67hm"
},
{
"name": "https://github.com/http4s/http4s/commit/6e8eccd64a6a74ab4811897881e95e0e1b3a818e",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/http4s/http4s/commit/6e8eccd64a6a74ab4811897881e95e0e1b3a818e"
},
{
"name": "https://github.com/http4s/http4s/releases/tag/v0.23.35",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/http4s/http4s/releases/tag/v0.23.35"
},
{
"name": "https://github.com/http4s/http4s/releases/tag/v1.0.0-M47",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/http4s/http4s/releases/tag/v1.0.0-M47"
}
],
"source": {
"advisory": "GHSA-vmm3-xgcx-67hm",
"discovery": "UNKNOWN"
},
"title": "Http4s: HTTP/2 Denial of Service with Ember Backend"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-54556",
"datePublished": "2026-08-26T14:10:22.349Z",
"dateReserved": "2026-06-15T19:04:14.456Z",
"dateUpdated": "2026-08-29T02:38:44.725Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"vulnrichment": {
"containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-54556\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-08-29T02:38:20.242464Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-08-29T02:38:39.375Z\"}}], \"cna\": {\"title\": \"Http4s: HTTP/2 Denial of Service with Ember Backend\", \"source\": {\"advisory\": \"GHSA-vmm3-xgcx-67hm\", \"discovery\": \"UNKNOWN\"}, \"metrics\": [{\"cvssV4_0\": {\"version\": \"4.0\", \"baseScore\": 8.2, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"PRESENT\", \"privilegesRequired\": \"NONE\", \"subIntegrityImpact\": \"NONE\", \"vulnIntegrityImpact\": \"NONE\", \"subAvailabilityImpact\": \"NONE\", \"vulnAvailabilityImpact\": \"HIGH\", \"subConfidentialityImpact\": \"NONE\", \"vulnConfidentialityImpact\": \"NONE\"}}], \"affected\": [{\"vendor\": \"http4s\", \"product\": \"http4s\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003c 0.23.35\"}, {\"status\": \"affected\", \"version\": \"\u003e= 1.0.0-M1, \u003c 1.0.0-M46\"}]}, {\"vendor\": \"org.http4s\", \"product\": \"http4s-ember-core_2.12\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003c 0.23.35\"}]}, {\"vendor\": \"org.http4s\", \"product\": \"http4s-ember-core_2.13\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003e= 1.0.0-M1, \u003c 1.0.0-M46\"}, {\"status\": \"affected\", \"version\": \"\u003c 0.23.35\"}]}, {\"vendor\": \"org.http4s\", \"product\": \"http4s-ember-core_3\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003e= 1.0.0-M1, \u003c 1.0.0-M46\"}, {\"status\": \"affected\", \"version\": \"\u003c 0.23.35\"}]}], \"references\": [{\"url\": \"https://github.com/http4s/http4s/security/advisories/GHSA-vmm3-xgcx-67hm\", \"name\": \"https://github.com/http4s/http4s/security/advisories/GHSA-vmm3-xgcx-67hm\", \"tags\": [\"x_refsource_CONFIRM\"]}, {\"url\": \"https://github.com/http4s/http4s/commit/6e8eccd64a6a74ab4811897881e95e0e1b3a818e\", \"name\": \"https://github.com/http4s/http4s/commit/6e8eccd64a6a74ab4811897881e95e0e1b3a818e\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/http4s/http4s/releases/tag/v0.23.35\", \"name\": \"https://github.com/http4s/http4s/releases/tag/v0.23.35\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/http4s/http4s/releases/tag/v1.0.0-M47\", \"name\": \"https://github.com/http4s/http4s/releases/tag/v1.0.0-M47\", \"tags\": [\"x_refsource_MISC\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, an unauthenticated HTTP/2 peer can cause an out-of-memory denial of service in the Ember backend with HTTP/2 enabled. The Hpack wrapper in ember-core/shared/src/main/scala/org/http4s/ember/core/h2/Hpack.scala concatenates HEADERS and CONTINUATION frame fragments and decodes them into a single List, but maxHeaderSize accounting does not include indexed headers or HPACK per-header overhead. A small compressed header block can therefore expand into a much larger decoded representation that remains in memory for processing. Servers exposed to untrusted HTTP/2 traffic and clients directed to an untrusted HTTP/2 server are affected, and concurrent malicious connections can exhaust the process heap. This issue is fixed in versions 0.23.35 and 1.0.0-M47.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-409\", \"description\": \"CWE-409: Improper Handling of Highly Compressed Data (Data Amplification)\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2026-08-26T14:10:22.349Z\"}}}",
"cveMetadata": "{\"cveId\": \"CVE-2026-54556\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-08-29T02:38:44.725Z\", \"dateReserved\": \"2026-06-15T19:04:14.456Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2026-08-26T14:10:22.349Z\", \"assignerShortName\": \"GitHub_M\"}",
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
Loading…
Loading…