CVE-2025-49812
published 2025-07-10CVE-2025-49812: In some mod_ssl configurations on Apache HTTP Server versions through to 2.4.63, an HTTP desynchronisation attack allows a man-in-the-middle attacker to hijack…
PriorityP343high7.4CVSS 3.1
AVNACHPRNUINSUCHIHAN
EPSS
0.52%
40.9th percentile
In some mod_ssl configurations on Apache HTTP Server versions through to 2.4.63, an HTTP desynchronisation attack allows a man-in-the-middle attacker to hijack an HTTP session via a TLS upgrade.
Only configurations using "SSLEngine optional" to enable TLS upgrades are affected. Users are recommended to upgrade to version 2.4.64, which removes support for TLS upgrade.
Affected
8 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| apache | http_server | < 2.4.64 | 2.4.64 |
| apache_software_foundation | apache_http_server | <= 2.4.63 | — |
| debian | apache2 | < apache2 2.4.65-1~deb12u1 (bookworm) | apache2 2.4.65-1~deb12u1 (bookworm) |
| msrc | azl3_httpd_2.4.62-1_on_azure_linux_3.0 | — | — |
| msrc | azl3_httpd_2.4.64-1_on_azure_linux_3.0 | — | — |
| msrc | cbl2_httpd_2.4.62-1_on_cbl_mariner_2.0 | — | — |
| msrc | cbl2_httpd_2.4.64-1_on_cbl_mariner_2.0 | — | — |
| ubuntu | apache2 | — | — |
CVSS provenance
nvdv3.17.4HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
osv7.5HIGH
vendor_ubuntu7.5HIGH
vendor_debian7.4HIGH
vendor_msrc7.4HIGH
vendor_redhat7.4HIGH
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Ubuntu
Apache HTTP Server regression
vendor_ubuntu·2026-05-29·CVSS 7.3
CVE-2023-38709 [HIGH] Apache HTTP Server regression
Title: Apache HTTP Server regression
Summary: USN-8338-1 introduced a regression in Apache HTTP Server
USN-8338-1 fixed vulnerabilities in Apache HTTP Server. The update
introduced a regression that prevented mod_http2 from loading on Ubuntu
18.04 LTS. This update fixes the problem.
We apologize for the inconvenience.
Original advisory details:
It was discovered that Apache HTTP Server incorrectly handled certain
response headers. An attacker could possibly use this issue to perform
HTTP response splitting attacks. This issue only affected Ubuntu 14.04
LTS. (CVE-2023-38709)
Will Dormann and David Warren discovered that Apache HTTP Server's HTTP/2
implementation did not properly reclaim memory when streams were reset by
clients. A remote attacker could possibly use this issue to cause
Ubuntu
Apache HTTP Server vulnerabilities
vendor_ubuntu·2026-05-28·CVSS 7.3
CVE-2023-38709 [HIGH] Apache HTTP Server vulnerabilities
Title: Apache HTTP Server vulnerabilities
Summary: Several security issues were fixed in Apache HTTP Server.
It was discovered that Apache HTTP Server incorrectly handled certain
response headers. An attacker could possibly use this issue to perform
HTTP response splitting attacks. This issue only affected Ubuntu 14.04
LTS. (CVE-2023-38709)
Will Dormann and David Warren discovered that Apache HTTP Server's HTTP/2
implementation did not properly reclaim memory when streams were reset by
clients. A remote attacker could possibly use this issue to cause Apache
HTTP Server to consume resources, leading to a denial of service. This
issue only affected Ubuntu 18.04 LTS. (CVE-2023-45802)
Keran Mu and Jianjun Chen discovered that Apache HTTP Server incorrectly
handled certain response headers.
Ubuntu
Apache HTTP Server vulnerabilities
vendor_ubuntu·2025-08-19·CVSS 7.5
CVE-2024-43204 [HIGH] Apache HTTP Server vulnerabilities
Title: Apache HTTP Server vulnerabilities
Summary: Several security issues were fixed in Apache HTTP Server.
USN-7639-1 fixed several vulnerabilities in Apache. This update
provides the corresponding update for Ubuntu 16.04 LTS, Ubuntu
18.04 LTS, Ubuntu 20.04 LTS, and addressed a regression
fix (LP: #2119395). CVE-2025-49630 and CVE-2025-53020 only
affected Ubuntu 18.04 LTS and Ubuntu 20.04 LTS.
Original advisory details:
It was discovered that the Apache HTTP Server incorrectly handled
certain Content-Type response headers. A remote attacker could
possibly use this issue to perform HTTP response splitting attacks.
(CVE-2024-42516)
xiaojunjie discovered that the Apache HTTP Server mod_proxy module
incorrectly handled certain requests. A remote attacker could
possibly use this issue to
Ubuntu
Apache HTTP Server vulnerabilities
vendor_ubuntu·2025-07-16·CVSS 7.5
CVE-2025-49812 [HIGH] Apache HTTP Server vulnerabilities
Title: Apache HTTP Server vulnerabilities
Summary: Several security issues were fixed in Apache HTTP Server.
It was discovered that the Apache HTTP Server incorrectly handled certain
Content-Type response headers. A remote attacker could possibly use this
issue to perform HTTP response splitting attacks. (CVE-2024-42516)
xiaojunjie discovered that the Apache HTTP Server mod_proxy module
incorrectly handled certain requests. A remote attacker could possibly use
this issue to send outbound proxy requests to an arbitrary URL.
(CVE-2024-43204)
John Runyon discovered that the Apache HTTP Server mod_ssl module
incorrectly escaped certain data. A remote attacker could possibly use this
issue to insert escape characters into log files. (CVE-2024-47252)
Sven Hebrok, Felix Cramer, Tim Storm, Ma
Red Hat
httpd: HTTP Session Hijack via a TLS upgrade
vendor_redhat·2025-07-14·CVSS 7.4
CVE-2025-49812 [HIGH] httpd: HTTP Session Hijack via a TLS upgrade
httpd: HTTP Session Hijack via a TLS upgrade
In some mod_ssl configurations on Apache HTTP Server versions through to 2.4.63, an HTTP desynchronisation attack allows a man-in-the-middle attacker to hijack an HTTP session via a TLS upgrade.
Only configurations using "SSLEngine optional" to enable TLS upgrades are affected. Users are recommended to upgrade to version 2.4.64, which removes support for TLS upgrade.
An HTTP session hijacking flaw was found in Apache httpd. In some mod_ssl configurations on Apache HTTP Server, an HTTP desynchronization attack allows a man-in-the-middle attacker to hijack an HTTP session via a TLS upgrade.
Statement: Only configurations using the \"SSLEngine optional\" to enable TLS upgrades are affected.
This vulnerability is rated Moderate rather than Import
Microsoft
Apache HTTP Server: mod_ssl TLS upgrade attack
vendor_msrc·2025-07-08·CVSS 7.4
CVE-2025-49812 [HIGH] CWE-287 Apache HTTP Server: mod_ssl TLS upgrade attack
Apache HTTP Server: mod_ssl TLS upgrade attack
FAQ: Is Azure Linux the only Microsoft product that includes this open-source library and is therefore potentially affected by this vulnerability?
One of the main benefits to our customers who choose to use the Azure Linux distro is the commitment to keep it up to date with the most recent and most secure versions of the open source libraries with which the distro is composed. Microsoft is committed to transparency in this work which is why we began publishing CSAF/VEX in October 2025. See this blog post for more information. If impact to additional products is identified, we will update the CVE to reflect this.
Mariner: Mariner
apache: apache
Customer Action Required: Yes
Remediation: CBL-Mariner Releases
Reference: https://learn.micros
Debian
CVE-2025-49812: apache2 - In some mod_ssl configurations on Apache HTTP Server versions through to 2.4.63,...
vendor_debian·2025·CVSS 7.4
CVE-2025-49812 [HIGH] CVE-2025-49812: apache2 - In some mod_ssl configurations on Apache HTTP Server versions through to 2.4.63,...
In some mod_ssl configurations on Apache HTTP Server versions through to 2.4.63, an HTTP desynchronisation attack allows a man-in-the-middle attacker to hijack an HTTP session via a TLS upgrade. Only configurations using "SSLEngine optional" to enable TLS upgrades are affected. Users are recommended to upgrade to version 2.4.64, which removes support for TLS upgrade.
Scope: local
bookworm: resolved (fixed in 2.4.65-1~deb12u1)
bullseye: resolved (fixed in 2.4.65-1~deb11u1)
forky: resolved (fixed in 2.4.64-1)
sid: resolved (fixed in 2.4.64-1)
trixie: resolved (fixed in 2.4.64-1)
OSV
apache2 vulnerabilities
osv·2025-08-19·CVSS 7.5
CVE-2025-49630 [HIGH] apache2 vulnerabilities
apache2 vulnerabilities
USN-7639-1 fixed several vulnerabilities in Apache. This update
provides the corresponding update for Ubuntu 16.04 LTS, Ubuntu
18.04 LTS, Ubuntu 20.04 LTS, and addressed a regression
fix (LP: #2119395). CVE-2025-49630 and CVE-2025-53020 only
affected Ubuntu 18.04 LTS and Ubuntu 20.04 LTS.
Original advisory details:
It was discovered that the Apache HTTP Server incorrectly handled
certain Content-Type response headers. A remote attacker could
possibly use this issue to perform HTTP response splitting attacks.
(CVE-2024-42516)
xiaojunjie discovered that the Apache HTTP Server mod_proxy module
incorrectly handled certain requests. A remote attacker could
possibly use this issue to send outbound proxy requests to an
arbitrary URL. (CVE-2024-43204)
John Runyon disco
OSV
apache2 vulnerabilities
osv·2025-07-16·CVSS 7.5
CVE-2024-42516 [HIGH] apache2 vulnerabilities
apache2 vulnerabilities
It was discovered that the Apache HTTP Server incorrectly handled certain
Content-Type response headers. A remote attacker could possibly use this
issue to perform HTTP response splitting attacks. (CVE-2024-42516)
xiaojunjie discovered that the Apache HTTP Server mod_proxy module
incorrectly handled certain requests. A remote attacker could possibly use
this issue to send outbound proxy requests to an arbitrary URL.
(CVE-2024-43204)
John Runyon discovered that the Apache HTTP Server mod_ssl module
incorrectly escaped certain data. A remote attacker could possibly use this
issue to insert escape characters into log files. (CVE-2024-47252)
Sven Hebrok, Felix Cramer, Tim Storm, Maximilian Radoy, and Juraj
Somorovsky discovered that the Apache HTTP Server mod_ssl mo
OSV
CVE-2025-49812: In some mod_ssl configurations on Apache HTTP Server versions through to 2
osv·2025-07-10·CVSS 7.4
CVE-2025-49812 [HIGH] CVE-2025-49812: In some mod_ssl configurations on Apache HTTP Server versions through to 2
In some mod_ssl configurations on Apache HTTP Server versions through to 2.4.63, an HTTP desynchronisation attack allows a man-in-the-middle attacker to hijack an HTTP session via a TLS upgrade. Only configurations using "SSLEngine optional" to enable TLS upgrades are affected. Users are recommended to upgrade to version 2.4.64, which removes support for TLS upgrade.
OSV
CVE-2025-49812: In some mod_ssl configurations on Apache HTTP Server versions through to 2
osv·2025-07-10·CVSS 7.4
CVE-2025-49812 [HIGH] CVE-2025-49812: In some mod_ssl configurations on Apache HTTP Server versions through to 2
In some mod_ssl configurations on Apache HTTP Server versions through to 2.4.63, an HTTP desynchronisation attack allows a man-in-the-middle attacker to hijack an HTTP session via a TLS upgrade.
Only configurations using "SSLEngine optional" to enable TLS upgrades are affected. Users are recommended to upgrade to version 2.4.64, which removes support for TLS upgrade.
GHSA
GHSA-2mcx-3xj5-wg86: In some mod_ssl configurations on Apache HTTP Server versions through to 2
ghsa_unreviewed·2025-07-10
CVE-2025-49812 [HIGH] CWE-287 GHSA-2mcx-3xj5-wg86: In some mod_ssl configurations on Apache HTTP Server versions through to 2
In some mod_ssl configurations on Apache HTTP Server versions through to 2.4.63, an HTTP desynchronisation attack allows a man-in-the-middle attacker to hijack an HTTP session via a TLS upgrade.
Only configurations using "SSLEngine optional" to enable TLS upgrades are affected. Users are recommended to upgrade to version 2.4.64, which removes support for TLS upgrade.
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
2025-07-10
Published