CVE-2025-62504
CVE-2025-62504 is a medium-severity vulnerability in Envoyproxy Envoy with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-416.
Key facts
- Severity: Medium (CVSS 3.x base score 6.5)
- EPSS exploit prediction: 0% (30th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2025-34836
- Weakness: CWE-416
- Affected product: Envoyproxy Envoy
- Published:
- Last modified:
Description
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.
Frequently asked questions
- What is CVE-2025-62504?
- 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.
- How severe is CVE-2025-62504?
- CVE-2025-62504 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
- Is CVE-2025-62504 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2025-62504?
- CVE-2025-62504 affects Envoyproxy Envoy. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2025-62504?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2025-62504 have an EU (EUVD) identifier?
- Yes. CVE-2025-62504 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-34836.
- When was CVE-2025-62504 published?
- CVE-2025-62504 was published on 2025-10-16 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*
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