NVD / CVE Program· CNA GitHub_M

CVE-2025-62504: Envoy Lua filter use-after-free when oversized rewritten response body causes crash

HighCVSS 7.5 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 30/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.43% (FIRST EPSS).
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
Fixed version: istioctl (openSUSE:Tumbleweed) 1.27.3-1.1.

Low priority for now. Upgrade to istioctl (openSUSE:Tumbleweed) 1.27.3-1.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Envoy is an open source edge and service proxy. Envoy versions earlier than 1.36.2, 1.35.6, 1.34.10, and 1.33.12 contain a use-after-free vulnerability in the Lua filter. When a Lua script executing in the response phase rewrites a response body so that its size exceeds the configured per_connection_buffer_limit_bytes (default 1MB), Envoy generates a local reply whose headers override the original response headers, leaving dangling references and causing a crash. This results in denial of service. Updating to versions 1.36.2, 1.35.6, 1.34.10, or 1.33.12 fixes the issue. Increasing per_connection_buffer_limit_bytes (and for HTTP/2 the initial_stream_window_size) or increasing per_request_buffer_limit_bytes / request_body_buffer_limit can reduce the likelihood of triggering the condition but does not correct the underlying memory safety flaw.

openSUSE-SU-2025:15655-1

Published: Oct 16, 2025
Updated: Oct 9, 2026
EPSS: 0.4% · 37th percentile
CWE: CWE-416

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 30 / 40 · 7.5 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.4%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: 7.5
CNA · GitHub_M: 6.5; 1.0 point gap

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
envoyproxy	envoy	cpe:2.3:a:envoyproxy:envoy

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

envoyproxy envoy
- >= 1.36.0, <= 1.36.1, >= 1.350, <= 1.35.5, >= 1.34.0, <= 1.34.9, <= 1.33.11affected

Affected versions · NVD (4)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

envoyproxy envoybefore 1.33.12
envoyproxy envoy1.34.0 and later · before 1.34.10
envoyproxy envoy1.35.0 and later · before 1.35.6
envoyproxy envoy1.36.0 and later · before 1.36.2

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
openSUSE:Tumbleweed	istioctl	before 1.27.3-1.1	1.27.3-1.1

Same product

envoyproxy: all records

Other highest-scoring records for the same primary product.

CVE-2024-30255HTTP/2: CPU exhaustion due to CONTINUATION frame flood
56Plan
CVE-2024-27919HTTP/2: memory exhaustion due to CONTINUATION frame flood
55Plan
CVE-2021-29492Bypass of path matching rules using escaped slash characters
52Plan

Published before and after this one in the same product

← EarlierCVE-2025-55162Sep 3, 2025 · Envoy: oAuth2 Filter Signout route will not clear cookies because of missing "secure;" flag
35Monitor
← EarlierCVE-2025-62409Oct 16, 2025 · Envoy allows large requests and responses to cause TCP connection pool crash
26Monitor
Later →CVE-2025-64527Dec 3, 2025 · Envoy crashes when JWT authentication is configured with the remote JWKS fetching
26Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
opensuse:istioctl	1.27.3-1.1 · openSUSE:Tumbleweed	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

CVE-2024-39305472 days apartEnvoy Proxy use after free when route hash policy is configured with cookie attributes
36Monitor
CVE-2025-5458844 days apartEnvoy: Race condition in Dynamic Forward Proxy leads to use-after-free and segmentation faults
30Monitor
CVE-2026-26330145 days apartEnvoy global rate limit may crash when the response phase limit is enabled and the response phase request is failed directly
30Monitor
CVE-2026-73512340 days apartEnvoy: use-after-free in QUIC on internal redirects
30Monitor
CVE-2024-32974499 days apartEnvoy affected by a crash in EnvoyQuicServerStream::OnInitialHeadersComplete()
30Monitor
CVE-2026-47207253 days apartEnvoy crashes if multiple unexpected ext_proc responses are packed into one gRPC message
26Monitor

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · public bounty program.

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
No account or password is required.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: none
Integrity: none
Availability: high · the service can be disrupted

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: None
Integrity impact: None
Availability impact: High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

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

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log (1)

Fix✗ → ✓Sep 28, 2026, 10:45 PM UTC

For records you follow, these changes also arrive as notifications. →

References

github.com/envoyproxy/envoy/security/advisories/GHSA-gcxr-6vrp-wff3

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records