High
Security advisory
The Apache HTTP Server 2.4.18 through 2.4.20, when mod_http2 and mod_ssl are enabled, does not properly recognize the "SSLVerifyClient require" directive for HTTP/2 request authorization, which allows remote attackers to bypass intended access restrictions by leveraging the ability to send multiple requests over a single connection and aborting a renegotiation.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2016-4979
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 12:09 UTC · Revision 1
Source evidence
The Apache HTTP Server 2.4.18 through 2.4.20, when mod_http2 and mod_ssl are enabled, does not properly recognize the "SSLVerifyClient require" directive for HTTP/2 request authorization, which allows remote attackers to bypass intended access restrictions by leveraging the ability to send multiple requests over a single connection and aborting a renegotiation.
osv:CVE-2016-4979
Complete source record
{
"id": "b78a9dac98c6bef9c9fdaf0ec0257863c2406f109c94488fb7cd3c4a5f096c14",
"url": "https://osv.dev/vulnerability/CVE-2016-4979",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2016-4979",
"summary": "The Apache HTTP Server 2.4.18 through 2.4.20, when mod_http2 and mod_ssl are enabled, does not properly recognize the \"SSLVerifyClient require\" directive for HTTP/2 request authorization, which allows remote attackers to bypass intended access restrictions by leveraging the ability to send multiple requests over a single connection and aborting a renegotiation.",
"evidence": "osv:CVE-2016-4979",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2016-4979",
"aliases": [
"CVE-2016-4979"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/apache/httpd",
"type": "GIT",
"events": [
{
"introduced": "b7ef32c4957883ab17105fa82e6331bf48bed78a"
},
{
"last_affected": "6e65a7f3dadcade4274ae53f734d4c35188e3786"
},
{
"fixed": "2d0e4eff04ea963128a41faaef21f987272e05a2"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:apache:http_server:2.4.18:*:*:*:*:*:*:*",
"range": [
{
"introduced": "2.4.18"
},
{
"last_affected": "2.4.18"
}
],
"source": "CPE_STRING"
},
{
"cpe": "cpe:2.3:a:apache:http_server:2.4.19:*:*:*:*:*:*:*",
"range": [
{
"introduced": "2.4.19"
},
{
"last_affected": "2.4.19"
}
],
"source": "CPE_STRING"
},
{
"cpe": "cpe:2.3:a:apache:http_server:2.4.20:*:*:*:*:*:*:*",
"range": [
{
"introduced": "2.4.20"
},
{
"last_affected": "2.4.20"
}
],
"source": "CPE_STRING"
},
{
"range": [
{
"fixed": "2d0e4eff04ea963128a41faaef21f987272e05a2"
}
],
"source": "REFERENCES_COMMIT"
}
]
}
}
],
"versions": [
"2.4.18",
"2.4.19",
"2.4.20"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2016-4979.json",
"vanir_signatures": [
{
"id": "CVE-2016-4979-5eec88a5",
"digest": {
"length": 13247,
"function_hash": "285512666638282015489581124945252142619"
},
"source": "https://github.com/apache/httpd/commit/2d0e4eff04ea963128a41faaef21f987272e05a2",
"target": {
"file": "modules/ssl/ssl_engine_kernel.c",
"function": "ssl_hook_Access"
},
"deprecated": false,
"signature_type": "Function",
"signature_version": "v1"
},
{
"id": "CVE-2016-4979-f37c52b9",
"digest": {
"threshold": 0.9,
"line_hashes": [
"244385919861610858721936967085811442209",
"308071227496002563137936932201529329994",
"158621415921638913253691990362977946518",
"320008290054834887054868414971497180225"
]
},
"source": "https://github.com/apache/httpd/commit/2d0e4eff04ea963128a41faaef21f987272e05a2",
"target": {
"file": "modules/ssl/ssl_engine_kernel.c"
},
"deprecated": false,
"signature_type": "Line",
"signature_version": "v1"
}
],
"vanir_signatures_modified": "2026-10-20T13:14:16Z"
}
}
],
"modified": "2026-10-20T13:14:16.968032064Z",
"provider": "osv",
"references": [
"https://lists.apache.org/thread.html/56c2e7cc9deb1c12a843d0dc251ea7fd3e7e80293cde02fcd65286ba%40%3Ccvs.httpd.apache.org%3E",
"https://lists.apache.org/thread.html/84a3714f0878781f6ed84473d1a503d2cc382277e100450209231830%40%3Ccvs.httpd.apache.org%3E",
"https://lists.apache.org/thread.html/r04e89e873d54116a0635ef2f7061c15acc5ed27ef7500997beb65d6f%40%3Ccvs.httpd.apache.org%3E",
"https://lists.apache.org/thread.html/r76142b8c5119df2178be7c2dba88fde552eedeec37ea993dfce68d1d%40%3Ccvs.httpd.apache.org%3E",
"https://lists.apache.org/thread.html/r9f93cf6dde308d42a9c807784e8102600d0397f5f834890708bf6920%40%3Ccvs.httpd.apache.org%3E",
"https://lists.apache.org/thread.html/rb14daf9cc4e28d18cdc15d6a6ca74e565672fabf7ad89541071d008b%40%3Ccvs.httpd.apache.org%3E",
"https://lists.apache.org/thread.html/rc998b18880df98bafaade071346690c2bc1444adaa1a1ea464b93f0a%40%3Ccvs.httpd.apache.org%3E",
"https://lists.apache.org/thread.html/rcc44594d4d6579b90deccd4536b5d31f099ef563df39b094be286b9e%40%3Ccvs.httpd.apache.org%3E",
"https://lists.apache.org/thread.html/rd18c3c43602e66f9cdcf09f1de233804975b9572b0456cc582390b6f%40%3Ccvs.httpd.apache.org%3E",
"https://lists.apache.org/thread.html/re1e3a24664d35bcd0a0e793e0b5fc6ca6c107f99a1b2c545c5d4b467%40%3Ccvs.httpd.apache.org%3E",
"https://lists.apache.org/thread.html/re3d27b6250aa8548b8845d314bb8a350b3df326cacbbfdfe4d455234%40%3Ccvs.httpd.apache.org%3E",
"https://lists.apache.org/thread.html/rf6449464fd8b7437704c55f88361b66f12d5b5f90bcce66af4be4ba9%40%3Ccvs.httpd.apache.org%3E",
"https://access.redhat.com/errata/RHSA-2016:1420",
"https://security.gentoo.org/glsa/201610-02",
"https://security.netapp.com/advisory/ntap-20180601-0001/",
"https://github.com/apache/httpd/commit/2d0e4eff04ea963128a41faaef21f987272e05a2"
],
"provider_metadata": {}
},
"related_cves": [
{
"value": "CVE-2016-4979",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 387359,
"published_at": "2016-07-06T14:59:04.487+00:00"
}