CVE-2026-63718VulnerabilityPublished 1 Oct 2026Updated 9 Nov 2026

Apache2: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') response smuggling

Affects apache2Source GCVE Database

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Authoritative record:CVE-2026-63718· High 7.5

Not known to be exploited · CVSS 7.5 High · fixed in 2.4.41-4ubuntu3.23+esm9 : patch apache2 soon.

Data as of 10 Nov 2026, 06:09 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

Patch: Available – fixed in 2.4.41-4ubuntu3.23+esm9, 2.4.52-1ubuntu4.25, 2.4.58-1ubuntu8.17 +1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: High
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 1 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 9 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Patches and advisories

ubuntu.com/security/notices/USN-8931-1 (opens in a new tab)

Affected software

Product	Affected	Fixed in
Ubuntu 26.10apache2`pkg:deb/ubuntu/apache2?arch=source&distro=stonking`Other threats	Affected =2.4.66-2ubuntu2 =2.4.68-1ubuntu4 =2.4.68-1ubuntu6.1	Fixed in–
Ubuntu 26.04 LTSapache2`pkg:deb/ubuntu/apache2?arch=source&distro=resolute`Other threats	Affected <2.4.66-2ubuntu2.6	Fixed in 2.4.66-2ubuntu2.6
Ubuntu 24.04 LTSapache2`pkg:deb/ubuntu/apache2?arch=source&distro=noble`Other threats	Affected <2.4.58-1ubuntu8.17	Fixed in 2.4.58-1ubuntu8.17
Ubuntu 22.04 LTSapache2`pkg:deb/ubuntu/apache2?arch=source&distro=jammy`Other threats	Affected <2.4.52-1ubuntu4.25	Fixed in 2.4.52-1ubuntu4.25
Ubuntu Pro 20.04 LTSapache2`pkg:deb/ubuntu/apache2?arch=source&distro=esm-infra/focal`Other threats	Affected <2.4.41-4ubuntu3.23+esm9	Fixed in 2.4.41-4ubuntu3.23+esm9

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available and has been released by Ubuntu in updated apache2 package versions for all affected LTS releases (20.04, 22.04, 24.04, 26.04). Users should apply the official security updates as provided in Ubuntu Security Notice USN-8931-1. Standard system updates will apply the necessary patches. No additional mitigation steps are required beyond applying these updates.

Description

Apache HTTP Server versions from 2.4.30 through 2.4.68 are affected by an HTTP request/response smuggling vulnerability in the mod_proxy_uwsgi module. This flaw involves inconsistent interpretation of HTTP requests, specifically crafted uwsgi responses with Transfer-Encoding headers. The vulnerability has a high severity score and could allow remote attackers to perform HTTP response smuggling attacks. Fixes have been released in multiple updated package versions across Ubuntu LTS releases.

Impact

The vulnerability allows a remote attacker to perform HTTP response smuggling attacks by exploiting inconsistent handling of HTTP requests and backend responses in mod_proxy_uwsgi. The CVSS v3.1 base score is 7.5 (High), indicating that the flaw can impact the integrity of the server without requiring privileges or user interaction. There is no indication of confidentiality or availability impact. No known exploits in the wild have been reported.

References

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