CVE-2026-77762 (GCVE-0-2026-77762)
Vulnerability from cvelistv5 – Published: 2026-09-23 11:19 – Updated: 2026-09-23 18:10
VLAI
EPSS
VEX
Title
Apache Tomcat: Stale HPACK emitter injects trailers into recycled pooled Request
Summary
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') vulnerability in Apache Tomcat allows an attacker to inject trailer fields into another HTTP/2 request.
This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.25, from 10.1.0-M1 through 10.1.59, from 9.0.39 through 9.0.121.
The following versions were EOL at the time the CVE was created but are
known to be affected: from 8.5.59 through 8.5.100. Other unsupported versions may also be affected.
Users are recommended to upgrade to version 11.0.26, 10.1.60, 9.0.122, which fix the issue.
Severity
8.1 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-23 15:40 UTC
CWE
- CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://lists.apache.org/thread/y5r9fvjo7ol24mkoy… | vendor-advisory |
| http://www.openwall.com/lists/oss-security/2026/0… |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Apache Software Foundation | Apache Tomcat |
Affected:
11.0.0-M1 , ≤ 11.0.25
(semver)
Affected: 10.1.0-M1 , ≤ 10.1.59 (semver) Affected: 9.0.39 , ≤ 9.0.121 (semver) Affected: 8.56.59 , ≤ 8.5.100 (semver) Unaffected: 0 , ≤ 7.0.109 (semver) |
guessed |
{
"containers": {
"adp": [
{
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "HIGH",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 8.1,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
}
},
{
"other": {
"content": {
"id": "CVE-2026-77762",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-09-23T15:40:01.556894Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-09-23T15:40:13.579Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
},
{
"providerMetadata": {
"dateUpdated": "2026-09-23T18:10:43.790Z",
"orgId": "af854a3a-2127-422b-91ae-364da2661108",
"shortName": "CVE"
},
"references": [
{
"url": "http://www.openwall.com/lists/oss-security/2026/09/23/23"
}
],
"title": "CVE Program Container"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Apache Tomcat",
"vendor": "Apache Software Foundation",
"versions": [
{
"lessThanOrEqual": "11.0.25",
"status": "affected",
"version": "11.0.0-M1",
"versionType": "semver"
},
{
"lessThanOrEqual": "10.1.59",
"status": "affected",
"version": "10.1.0-M1",
"versionType": "semver"
},
{
"lessThanOrEqual": "9.0.121",
"status": "affected",
"version": "9.0.39",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.5.100",
"status": "affected",
"version": "8.56.59",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.0.109",
"status": "unaffected",
"version": "0",
"versionType": "semver"
}
]
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eConcurrent Execution using Shared Resource with Improper Synchronization (\u0027Race Condition\u0027) vulnerability in Apache Tomcat allows an attacker to inject trailer fields into another HTTP/2 request.\u003c/p\u003e\u003cp\u003eThis issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.25, from 10.1.0-M1 through 10.1.59, from 9.0.39 through 9.0.121.\u003c/p\u003e\u003cp\u003eThe following versions were EOL at the time the CVE was created but are \nknown to be affected: from 8.5.59 through 8.5.100. Other unsupported versions may also be affected.\u003cbr\u003e\u003c/p\u003e\u003cp\u003eUsers are recommended to upgrade to version 11.0.26, 10.1.60, 9.0.122, which fix\u0026nbsp;the issue.\u003c/p\u003e"
}
],
"value": "Concurrent Execution using Shared Resource with Improper Synchronization (\u0027Race Condition\u0027) vulnerability in Apache Tomcat allows an attacker to inject trailer fields into another HTTP/2 request.\n\n\n\nThis issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.25, from 10.1.0-M1 through 10.1.59, from 9.0.39 through 9.0.121.\n\n\n\nThe following versions were EOL at the time the CVE was created but are \nknown to be affected: from 8.5.59 through 8.5.100. Other unsupported versions may also be affected.\n\n\n\n\nUsers are recommended to upgrade to version 11.0.26, 10.1.60, 9.0.122, which fix\u00a0the issue."
}
],
"metrics": [
{
"other": {
"content": {
"text": "low"
},
"type": "Textual description of severity"
},
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-362",
"description": "CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization (\u0027Race Condition\u0027)",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-09-23T11:19:28.370Z",
"orgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09",
"shortName": "apache"
},
"references": [
{
"tags": [
"vendor-advisory"
],
"url": "https://lists.apache.org/thread/y5r9fvjo7ol24mkoyoc0st8bqrfyqcyn"
}
],
"source": {
"discovery": "INTERNAL"
},
"title": "Apache Tomcat: Stale HPACK emitter injects trailers into recycled pooled Request",
"x_generator": {
"engine": "Vulnogram 0.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09",
"assignerShortName": "apache",
"cveId": "CVE-2026-77762",
"datePublished": "2026-09-23T11:19:28.370Z",
"dateReserved": "2026-08-21T10:14:30.089Z",
"dateUpdated": "2026-09-23T18:10:43.790Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-77762",
"date": "2026-09-24",
"epss": "0.00361",
"percentile": "0.27089"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Apache Tomcat",
"vendor": "Apache Software Foundation",
"versions": [
{
"lessThanOrEqual": "11.0.25",
"status": "affected",
"version": "11.0.0-M1",
"versionType": "semver"
},
{
"lessThanOrEqual": "10.1.59",
"status": "affected",
"version": "10.1.0-M1",
"versionType": "semver"
},
{
"lessThanOrEqual": "9.0.121",
"status": "affected",
"version": "9.0.39",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.5.100",
"status": "affected",
"version": "8.56.59",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.0.109",
"status": "unaffected",
"version": "0",
"versionType": "semver"
}
]
}
],
"source": "security@apache.org"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Concurrent Execution using Shared Resource with Improper Synchronization (\u0027Race Condition\u0027) vulnerability in Apache Tomcat allows an attacker to inject trailer fields into another HTTP/2 request.\n\n\n\nThis issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.25, from 10.1.0-M1 through 10.1.59, from 9.0.39 through 9.0.121.\n\n\n\nThe following versions were EOL at the time the CVE was created but are \nknown to be affected: from 8.5.59 through 8.5.100. Other unsupported versions may also be affected.\n\n\n\n\nUsers are recommended to upgrade to version 11.0.26, 10.1.60, 9.0.122, which fix\u00a0the issue."
}
],
"id": "CVE-2026-77762",
"lastModified": "2026-09-23T19:19:18.870",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "HIGH",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 8.1,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 2.2,
"impactScore": 5.9,
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-77762",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-09-23T15:40:01.556894Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-09-23T12:17:06.800",
"references": [
{
"source": "security@apache.org",
"url": "https://lists.apache.org/thread/y5r9fvjo7ol24mkoyoc0st8bqrfyqcyn"
},
{
"source": "af854a3a-2127-422b-91ae-364da2661108",
"url": "http://www.openwall.com/lists/oss-security/2026/09/23/23"
}
],
"sourceIdentifier": "security@apache.org",
"vulnStatus": "Awaiting Analysis",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-362"
}
],
"source": "security@apache.org",
"type": "Secondary"
}
]
}
},
"vulnrichment": {
"containers": {
"adp": [
{
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "HIGH",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 8.1,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
}
},
{
"other": {
"content": {
"id": "CVE-2026-77762",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-09-23T15:40:01.556894Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-09-23T15:39:51.989Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Apache Tomcat",
"vendor": "Apache Software Foundation",
"versions": [
{
"lessThanOrEqual": "11.0.25",
"status": "affected",
"version": "11.0.0-M1",
"versionType": "semver"
},
{
"lessThanOrEqual": "10.1.59",
"status": "affected",
"version": "10.1.0-M1",
"versionType": "semver"
},
{
"lessThanOrEqual": "9.0.121",
"status": "affected",
"version": "9.0.39",
"versionType": "semver"
},
{
"lessThanOrEqual": "8.5.100",
"status": "affected",
"version": "8.56.59",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.0.109",
"status": "unaffected",
"version": "0",
"versionType": "semver"
}
]
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eConcurrent Execution using Shared Resource with Improper Synchronization (\u0027Race Condition\u0027) vulnerability in Apache Tomcat allows an attacker to inject trailer fields into another HTTP/2 request.\u003c/p\u003e\u003cp\u003eThis issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.25, from 10.1.0-M1 through 10.1.59, from 9.0.39 through 9.0.121.\u003c/p\u003e\u003cp\u003eThe following versions were EOL at the time the CVE was created but are \nknown to be affected: from 8.5.59 through 8.5.100. Other unsupported versions may also be affected.\u003cbr\u003e\u003c/p\u003e\u003cp\u003eUsers are recommended to upgrade to version 11.0.26, 10.1.60, 9.0.122, which fix\u0026nbsp;the issue.\u003c/p\u003e"
}
],
"value": "Concurrent Execution using Shared Resource with Improper Synchronization (\u0027Race Condition\u0027) vulnerability in Apache Tomcat allows an attacker to inject trailer fields into another HTTP/2 request.\n\n\n\nThis issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.25, from 10.1.0-M1 through 10.1.59, from 9.0.39 through 9.0.121.\n\n\n\nThe following versions were EOL at the time the CVE was created but are \nknown to be affected: from 8.5.59 through 8.5.100. Other unsupported versions may also be affected.\n\n\n\n\nUsers are recommended to upgrade to version 11.0.26, 10.1.60, 9.0.122, which fix\u00a0the issue."
}
],
"metrics": [
{
"other": {
"content": {
"text": "low"
},
"type": "Textual description of severity"
},
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-362",
"description": "CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization (\u0027Race Condition\u0027)",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-09-23T11:19:28.370Z",
"orgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09",
"shortName": "apache"
},
"references": [
{
"tags": [
"vendor-advisory"
],
"url": "https://lists.apache.org/thread/y5r9fvjo7ol24mkoyoc0st8bqrfyqcyn"
}
],
"source": {
"discovery": "INTERNAL"
},
"title": "Apache Tomcat: Stale HPACK emitter injects trailers into recycled pooled Request",
"x_generator": {
"engine": "Vulnogram 0.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09",
"assignerShortName": "apache",
"cveId": "CVE-2026-77762",
"datePublished": "2026-09-23T11:19:28.370Z",
"dateReserved": "2026-08-21T10:14:30.089Z",
"dateUpdated": "2026-09-23T15:40:13.579Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
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.
Loading…
Loading…
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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Loading…
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
Loading…