MEDIUM
httpd: mod_http2 denial-of-service by thread starvation
Published Jul 6, 2016
5.9
MEDIUMCVSS 3.0
EPSS 15.92%
Description
The Apache HTTP Server 2.4.17 and 2.4.18, when mod_http2 is enabled, does not limit the number of simultaneous stream workers for a single HTTP/2 connection, which allows remote attackers to cause a denial of service (stream-processing outage) via modified flow-control windows.
Affected products
No data.
OR
- 2.4.17
- 2.4.18
No data.
Red Hat Software Collections for Red Hat Enterprise Linux 6
httpd24-httpd-0:2.4.25-9.el6
Fixed · RHSA-2017:1161
Red Hat Software Collections for Red Hat Enterprise Linux 6.7 EUS
httpd24-httpd-0:2.4.25-9.el6
Fixed · RHSA-2017:1161
Red Hat Software Collections for Red Hat Enterprise Linux 7
httpd24-httpd-0:2.4.25-9.el7
Fixed · RHSA-2017:1161
Red Hat Software Collections for Red Hat Enterprise Linux 7.3 EUS
httpd24-httpd-0:2.4.25-9.el7
Fixed · RHSA-2017:1161
CloudForms Management Engine 5
httpd
Not affected
Red Hat Directory Server 8
httpd
Not affected
Red Hat Enterprise Linux 5
httpd
Not affected
Red Hat Enterprise Linux 6
httpd
Not affected
Red Hat Enterprise Linux 7
httpd
Not affected
Red Hat JBoss Enterprise Application Platform 5
httpd
Not affected
Red Hat JBoss Enterprise Application Platform 6
httpd
Not affected
Red Hat JBoss Enterprise Web Server 1
httpd
Not affected
Red Hat JBoss Enterprise Web Server 2
httpd
Not affected
Red Hat JBoss Enterprise Web Server 3
httpd
Not affected
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Software Collections for Red Hat Enterprise Linux 6 | httpd24-httpd-0:2.4.25-9.el6 | Fixed | RHSA-2017:1161 |
| Red Hat Software Collections for Red Hat Enterprise Linux 6.7 EUS | httpd24-httpd-0:2.4.25-9.el6 | Fixed | RHSA-2017:1161 |
| Red Hat Software Collections for Red Hat Enterprise Linux 7 | httpd24-httpd-0:2.4.25-9.el7 | Fixed | RHSA-2017:1161 |
| Red Hat Software Collections for Red Hat Enterprise Linux 7.3 EUS | httpd24-httpd-0:2.4.25-9.el7 | Fixed | RHSA-2017:1161 |
| CloudForms Management Engine 5 | httpd | Not affected | n/a |
| Red Hat Directory Server 8 | httpd | Not affected | n/a |
| Red Hat Enterprise Linux 5 | httpd | Not affected | n/a |
| Red Hat Enterprise Linux 6 | httpd | Not affected | n/a |
| Red Hat Enterprise Linux 7 | httpd | Not affected | n/a |
| Red Hat JBoss Enterprise Application Platform 5 | httpd | Not affected | n/a |
| Red Hat JBoss Enterprise Application Platform 6 | httpd | Not affected | n/a |
| Red Hat JBoss Enterprise Web Server 1 | httpd | Not affected | n/a |
| Red Hat JBoss Enterprise Web Server 2 | httpd | Not affected | n/a |
| Red Hat JBoss Enterprise Web Server 3 | httpd | Not affected | n/a |
No package ranges for this CVE.
Remediation
No remediation recorded yet.
Metrics
No CVSS v4.0 score for this CVE.
No CVSS v3.1 score for this CVE.
5.9 MEDIUM NVD
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector Network
Attack Complexity High
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality Impact None
Integrity Impact None
Availability Impact High
4.3 MEDIUM NVD
AV:N/AC:M/Au:N/C:N/I:N/A:P
Access Vector Network
Access Complexity Medium
Authentication None
Confidentiality Impact None
Integrity Impact None
Availability Impact Partial
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
15.92% 0.15923
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 2, 2026.
EPSS probability 0.15923
Score over time
2022–2026- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Percentile over time
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Table of values (52 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 2, 2026 | 15.92% (0.15923) | 96.80th | v5 (v2026.06.15) |
| Sep 5, 2026 | 16.36% (0.16362) | 96.81th | v5 (v2026.06.15) |
| Jun 15, 2026 | 15.33% (0.15327) | 96.34th | v5 (v2026.06.15) |
| Jun 9, 2026 | 51.81% (0.51806) | 97.96th | v4 (v2025.03.14) |
| Mar 8, 2026 | 41.88% (0.41883) | 97.36th | v4 (v2025.03.14) |
| Mar 4, 2026 | 43.33% (0.43333) | 97.43th | v4 (v2025.03.14) |
| Mar 1, 2026 | 35.67% (0.35669) | 97.00th | v4 (v2025.03.14) |
| Feb 18, 2026 | 43.33% (0.43333) | 97.41th | v4 (v2025.03.14) |
| Feb 4, 2026 | 36.84% (0.36839) | 97.03th | v4 (v2025.03.14) |
| Feb 1, 2026 | 29.57% (0.29572) | 96.52th | v4 (v2025.03.14) |
| Jan 4, 2026 | 36.84% (0.36839) | 97.00th | v4 (v2025.03.14) |
| Jan 1, 2026 | 29.57% (0.29572) | 96.49th | v4 (v2025.03.14) |
| Dec 28, 2025 | 36.84% (0.36839) | 96.99th | v4 (v2025.03.14) |
| Dec 27, 2025 | 29.91% (0.29910) | 96.51th | v4 (v2025.03.14) |
| Dec 18, 2025 | 36.84% (0.36839) | 96.98th | v4 (v2025.03.14) |
| Dec 4, 2025 | 45.29% (0.45286) | 97.44th | v4 (v2025.03.14) |
| Dec 1, 2025 | 37.60% (0.37598) | 97.04th | v4 (v2025.03.14) |
| Nov 4, 2025 | 45.29% (0.45286) | 97.45th | v4 (v2025.03.14) |
| Nov 1, 2025 | 37.60% (0.37598) | 97.03th | v4 (v2025.03.14) |
| Oct 29, 2025 | 45.29% (0.45286) | 97.44th | v4 (v2025.03.14) |
| Oct 28, 2025 | 40.82% (0.40817) | 97.19th | v4 (v2025.03.14) |
| Oct 27, 2025 | 37.93% (0.37930) | 97.04th | v4 (v2025.03.14) |
| Oct 18, 2025 | 40.82% (0.40817) | 97.19th | v4 (v2025.03.14) |
| Oct 16, 2025 | 45.29% (0.45286) | 97.44th | v4 (v2025.03.14) |
| Oct 14, 2025 | 40.82% (0.40817) | 97.19th | v4 (v2025.03.14) |
| Oct 13, 2025 | 45.29% (0.45286) | 97.43th | v4 (v2025.03.14) |
| Oct 4, 2025 | 40.82% (0.40817) | 97.27th | v4 (v2025.03.14) |
| Sep 27, 2025 | 37.93% (0.37930) | 97.12th | v4 (v2025.03.14) |
| Sep 4, 2025 | 32.44% (0.32440) | 96.71th | v4 (v2025.03.14) |
| Sep 2, 2025 | 25.64% (0.25635) | 96.07th | v4 (v2025.03.14) |
| Sep 1, 2025 | 20.69% (0.20686) | 95.41th | v4 (v2025.03.14) |
| Aug 16, 2025 | 22.78% (0.22779) | 95.65th | v4 (v2025.03.14) |
| Aug 4, 2025 | 25.39% (0.25386) | 95.98th | v4 (v2025.03.14) |
| Aug 1, 2025 | 23.14% (0.23141) | 95.74th | v4 (v2025.03.14) |
| Jul 30, 2025 | 25.39% (0.25386) | 95.98th | v4 (v2025.03.14) |
| Jul 4, 2025 | 31.85% (0.31845) | 96.59th | v4 (v2025.03.14) |
| Jul 1, 2025 | 29.30% (0.29301) | 96.39th | v4 (v2025.03.14) |
| Jun 4, 2025 | 32.20% (0.32195) | 96.58th | v4 (v2025.03.14) |
| Jun 1, 2025 | 29.30% (0.29301) | 96.35th | v4 (v2025.03.14) |
| May 30, 2025 | 32.20% (0.32195) | 96.58th | v4 (v2025.03.14) |
| May 4, 2025 | 41.19% (0.41194) | 97.19th | v4 (v2025.03.14) |
| May 1, 2025 | 37.60% (0.37598) | 96.97th | v4 (v2025.03.14) |
| Mar 17, 2025 | 41.19% (0.41194) | 97.07th | v4 (v2025.03.14) |
| Mar 13, 2025 | 47.61% (0.47611) | 97.64th | v3 (v2023.03.01) |
| Jan 29, 2025 | 32.48% (0.32479) | 97.08th | v3 (v2023.03.01) |
| Dec 17, 2024 | 25.76% (0.25761) | 96.71th | v3 (v2023.03.01) |
| Oct 7, 2023 | 4.61% (0.04613) | 91.59th | v3 (v2023.03.01) |
| Jul 19, 2023 | 3.83% (0.03831) | 90.68th | v3 (v2023.03.01) |
| Mar 7, 2023 | 2.70% (0.02697) | 88.81th | v3 (v2023.03.01) |
| Mar 6, 2023 | 7.34% (0.07344) | 92.59th | v2 (v2022.01.01) |
| Apr 1, 2022 | 7.34% (0.07344) | 91.87th | v2 (v2022.01.01) |
| Feb 4, 2022 | 7.34% (0.07344) | 80.64th | v2 (v2022.01.01) |
Weaknesses (1)
References (25)
- http://httpd.apache.org/security/vulnerabilities_24.html x_refsource_CONFIRMPatchVendor Advisory
- http://svn.apache.org/viewvc?view=revision&revision=1733727 x_refsource_CONFIRM
- http://www.apache.org/dist/httpd/CHANGES_2.4 x_refsource_CONFIRM
- http://www.oracle.com/technetwork/security-advisory/cpuoct2016-2881722.html x_refsource_CONFIRM
- http://www.oracle.com/technetwork/topics/security/bulletinoct2016-3090566.html x_refsource_CONFIRM
- http://www.securityfocus.com/bid/92331 vdb-entryx_refsource_BID
- https://access.redhat.com/errata/RHSA-2017:1161 vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2016-1546 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1336350 Issue Tracking
- https://lists.apache.org/thread.html/56c2e7cc9deb1c12a843d0dc251ea7fd3e7e80293cde02fcd65286ba%40%3Ccvs.httpd.apache.org%3E mailing-listx_refsource_MLIST
- https://lists.apache.org/thread.html/84a3714f0878781f6ed84473d1a503d2cc382277e100450209231830%40%3Ccvs.httpd.apache.org%3E mailing-listx_refsource_MLIST
- https://lists.apache.org/thread.html/r04e89e873d54116a0635ef2f7061c15acc5ed27ef7500997beb65d6f%40%3Ccvs.httpd.apache.org%3E mailing-listx_refsource_MLIST
- https://lists.apache.org/thread.html/r76142b8c5119df2178be7c2dba88fde552eedeec37ea993dfce68d1d%40%3Ccvs.httpd.apache.org%3E mailing-listx_refsource_MLIST
- https://lists.apache.org/thread.html/r9f93cf6dde308d42a9c807784e8102600d0397f5f834890708bf6920%40%3Ccvs.httpd.apache.org%3E mailing-listx_refsource_MLIST
- https://lists.apache.org/thread.html/rb14daf9cc4e28d18cdc15d6a6ca74e565672fabf7ad89541071d008b%40%3Ccvs.httpd.apache.org%3E mailing-listx_refsource_MLIST
- https://lists.apache.org/thread.html/rc998b18880df98bafaade071346690c2bc1444adaa1a1ea464b93f0a%40%3Ccvs.httpd.apache.org%3E mailing-listx_refsource_MLIST
- https://lists.apache.org/thread.html/rcc44594d4d6579b90deccd4536b5d31f099ef563df39b094be286b9e%40%3Ccvs.httpd.apache.org%3E mailing-listx_refsource_MLIST
- https://lists.apache.org/thread.html/rd18c3c43602e66f9cdcf09f1de233804975b9572b0456cc582390b6f%40%3Ccvs.httpd.apache.org%3E mailing-listx_refsource_MLIST
- https://lists.apache.org/thread.html/re1e3a24664d35bcd0a0e793e0b5fc6ca6c107f99a1b2c545c5d4b467%40%3Ccvs.httpd.apache.org%3E mailing-listx_refsource_MLIST
- https://lists.apache.org/thread.html/re3d27b6250aa8548b8845d314bb8a350b3df326cacbbfdfe4d455234%40%3Ccvs.httpd.apache.org%3E mailing-listx_refsource_MLIST
- https://lists.apache.org/thread.html/rf6449464fd8b7437704c55f88361b66f12d5b5f90bcce66af4be4ba9%40%3Ccvs.httpd.apache.org%3E mailing-listx_refsource_MLIST
- https://nvd.nist.gov/vuln/detail/CVE-2016-1546
- https://security.gentoo.org/glsa/201610-02 vendor-advisoryx_refsource_GENTOO
- https://security.netapp.com/advisory/ntap-20180601-0001/ x_refsource_CONFIRM
- https://www.cve.org/CVERecord?id=CVE-2016-1546
Change history (0)
No recorded changes yet.
Sources
CVE.org / MITRE
Status PUBLISHED
Assigner certcc
Published Jul 6, 2016
Updated Aug 5, 2024
Reserved Jan 7, 2016
Link CVE-2016-1546
CISA Vulnrichment
Updated n/a