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VulnerabilityPublished

CVE-2026-26330: envoyproxy envoy · Use After Free

Affects envoyproxy envoySource CVE Database V5

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Not known to be exploited · CVSS 5.3 Medium · fixed in 1.37.1 : update envoyproxy envoy when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
5.3Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 26% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 1.37.1, 1.36.5, 1.35.9 +1
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 10 Mar 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 30 Oct 2026.

What to do

Upgrade envoy to 1.37.1, 1.36.5, 1.35.9 or 1.34.13; envoyproxy/envoy to 1.34.13.

Affected software

ProductAffectedFixed in
envoyproxyenvoyAffected
  • >=1.37.0 <1.37.1
Fixed in
  • 1.37.1
envoyproxyenvoyAffected
  • >=1.36.0 <1.36.5
Fixed in
  • 1.36.5
envoyproxyenvoyAffected
  • >=1.35.0 <1.35.9
Fixed in
  • 1.35.9
envoyproxyenvoyAffected
  • <1.34.13
Fixed in
  • 1.34.13
GitHubenvoyproxy/envoypkg:github/envoyproxy/envoyOther threatsAffected
  • <1.34.13
Fixed in
  • 1.34.13

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

AI-suggested

To mitigate CVE-2026-26330, organizations should upgrade Envoy to versions 1.37.1, 1.36.5, 1.35.8, or 1.34.13 or later, where the vulnerability has been fixed. Until upgrades can be applied, administrators should review and potentially disable the response phase rate limit with apply_on_stream_done enabled, or avoid enabling both request and response phase rate limits simultaneously to reduce exposure. Monitoring Envoy logs for crashes or unusual rate limit failures can help detect attempted exploitation. Implementing redundancy and failover mechanisms for Envoy proxies can minimize service disruption if crashes occur. Network-level protections such as rate limiting and filtering can reduce the likelihood of triggering the failure conditions remotely. Additionally, security teams should audit configurations to ensure that only necessary rate limiting features are enabled and that they are tested for stability under failure scenarios. Finally, maintaining an up-to-date inventory of Envoy versions in use across environments will facilitate timely patch management.

Description

Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, At the rate limit filter, if the response phase limit with apply_on_stream_done in the rate limit configuration is enabled and the response phase limit request fails directly, it may crash Envoy. When both the request phase limit and response phase limit are enabled, the safe gRPC client instance will be re-used for both the request phase request and response phase request. But after the request phase request is done, the inner state of the request phase limit request in gRPC client is not cleaned up. When a second limit request is sent at response phase, and the second limit request fails directly, the previous request's inner state may be accessed and result in crash. This vulnerability is fixed in 1.37.1, 1.36.5, 1.35.8, and 1.34.13.

References

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