VulnerabilityPublished 18 Apr 2024Updated 5 Nov 2026

CVE-2024-32475: envoyproxy envoy · Incorrect Check of Function Return Value

Affects envoyproxy envoySource CVE Database V5

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Not known to be exploited · CVSS 7.5 High · fixed in 1.30.1 : patch envoyproxy envoy soon.

Data as of 5 Nov 2026, 16:17 UTC

CVSS 3.1 base score

7.5High

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

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	7.5

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers can reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2024-04-23.

Patch

Available – fixed in 1.30.1, 1.29.4, 1.28.3 +1

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

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

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: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Apr 2024
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 5 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 envoyproxy envoy to 1.30.1, 1.29.4, 1.28.3 or 1.27.5.

Affected software

Product	Affected	Fixed in
envoyproxyenvoy	Affected >=1.30.0 <1.30.1	Fixed in 1.30.1
envoyproxyenvoy	Affected >=1.29.0 <1.29.4	Fixed in 1.29.4
envoyproxyenvoy	Affected >=1.28.0 <1.28.3	Fixed in 1.28.3
envoyproxyenvoy	Affected >=1.13.0 <1.27.5	Fixed in 1.27.5

AI-suggested

Upgrade Envoy to one of the fixed versions: 1.30.1, 1.29.4, 1.28.3, or 1.27.5. These versions include the fix that properly handles errors when setting the SNI for outbound TLS connections. Until upgraded, consider disabling auto_sni or implementing input validation to reject requests with host or :authority headers longer than 255 characters to prevent triggering the crash.

Description

CVE-2024-32475 is a vulnerability in Envoy proxy where an upstream TLS cluster with auto_sni enabled can cause the Envoy process to terminate abnormally if a request contains a host or :authority header longer than 255 characters. This happens because Envoy attempts to use the header value as the SNI for outbound TLS connections without properly handling errors when the SNI length exceeds the 255-character limit defined by the standard. The issue is fixed in versions 1.30.1, 1.29.4, 1.28.3, and 1.27.5.

Impact

Successful exploitation causes the Envoy process to terminate abnormally, resulting in a denial of service (DoS) condition. There is no impact on confidentiality or integrity. The vulnerability does not require privileges or user interaction and can be triggered remotely by sending a specially crafted request with an excessively long host or :authority header.

Summary

Envoy proxy versions prior to 1.30.1, 1.29.4, 1.28.3, and 1.27.5 contain a vulnerability where the process can crash due to improper handling of the Server Name Indication (SNI) length in TLS connections. When auto_sni is enabled and a request includes a host or :authority header exceeding 255 characters, Envoy tries to set the SNI to this value. Since the SNI length is limited to 255 characters by the TLS standard, this operation fails. Envoy does not check the return value of the SNI setting function correctly and aborts the process instead of handling the error gracefully. This vulnerability is tracked as CWE-253 (Incorrect Check of Function Return Value) and CWE-617 (Reachable Assertion).

CWE-253Incorrect Check of Function Return Value (opens in a new tab)
Base weaknessLikelihood of exploit: Low
The product incorrectly checks a return value from a function, which prevents it from detecting errors or exceptional conditions.
Architecture and Design · Language Selection
Use a language or compiler that uses exceptions and requires the catching of those exceptions.
Implementation
Properly check all functions which return a value.
Implementation
When designing any function make sure you return a value or throw an exception in case of an error.
OWASP ASVS 4.0.3
V11.1.7 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-617Reachable Assertion (opens in a new tab)
Base weakness
The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.
Implementation
If the assertion statement is required (e.g., for security or reliability), change the invoking code to avoid the conditions that trigger the assertion.
Implementation
Consider changing the assertion to some other less "fatal" error. This might not be easy to implement, since other code may be needed to handle the error.
Implementation
Make sensitive open/close operations non-reachable from directly user-controlled data (e.g. open/close resources)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 5 Nov 2026, 16:17 UTC

WeaknessesCWE-253, CWE-617

Technical details

References

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