--- title: Announcing Istio 1.28.9 | daily.dev description: Istio 1.28.9 is a patch release focused entirely on security fixes. It addresses 13 Envoy CVEs covering a range of vulnerabilities including: a... canonical: https://daily.dev/posts/announcing-istio-1-28-9-jnb76bnms twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Announcing Istio 1.28.9 | daily.dev og:description: Istio 1.28.9 is a patch release focused entirely on security fixes. It addresses 13 Envoy CVEs covering a range of vulnerabilities including: a... og:url: https://daily.dev/posts/announcing-istio-1-28-9-jnb76bnms og:image: https://api.daily.dev/og/posts/JnB76BnMS.png og:image:alt: Announcing Istio 1.28.9 og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Announcing Istio 1.28.9 **[Istio](https://daily.dev/sources/istio)** · 3 min read · 2 upvotes · 0 comments ## Summary Istio 1.28.9 is a patch release focused entirely on security fixes. It addresses 13 Envoy CVEs covering a range of vulnerabilities including: a denial-of-service via HTTP/3 QPACK blocked decoding (CVSS 7.5), a PROXY protocol header smuggling bug (CVSS 4.8), ext_proc filter issues (CVSS 6.5), use-after-free crashes in ext_authz and OAuth2 filters, a memory exhaustion flaw in the Zstd decompressor (CVSS 7.5), SAN validation bypass via NUL byte injection (CVSS 4.4), a gRPC stats filter crash (CVSS 6.5), HTTP/3 content-length validation issues (CVSS 7.5), a padding oracle in OAuth2 AES-256-CBC cookie decryption (CVSS 6.8), and a JSON nesting depth limit to prevent DoS (CVSS 7.5). Users running Istio 1.28.x are advised to upgrade. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What security vulnerabilities does Istio 1.28.9 fix? Istio 1.28.9 patches a batch of Envoy CVEs, including a CVSS 7.5 HTTP/3 QPACK denial-of-service bug causing unbounded memory growth, a CVSS 7.5 Zstd decompressor memory exhaustion issue, a CVSS 6.8 OAuth2 filter padding oracle in AES-256-CBC cookie decryption (now fixed by adding AES-256-GCM support), and a CVSS 4.4 SAN validation bypass via embedded NUL bytes in peer certificates. _Track security patch releases like this one on daily.dev before rolling Istio upgrades into production._ ### How was the Envoy OAuth2 filter padding oracle vulnerability fixed? The Envoy OAuth2 filter's AES-256-CBC cookie decryption had a padding oracle, tracked as CVE-2026-47775 with CVSS 6.8. The fix adds support for AES-256-GCM encryption, identified by a 'gcm.' algorithm marker, which authenticates the ciphertext and removes the oracle, replacing the vulnerable CBC-only decryption path. _Engineers hardening service mesh auth flows can follow fixes like this via daily.dev._ ### What changed between Istio 1.28.8 and 1.28.9? Istio 1.28.9 is a patch release containing bug fixes to improve robustness plus a security update pulling in numerous Envoy CVE fixes, covering HTTP/3, gRPC stats filters, ext_authz use-after-free crashes, TcpStatsdSink buffer overflows, JSON nesting depth limits, and PROXY protocol TLV smuggling, among other issues. _daily.dev helps teams stay current on point-release changes before upgrading Istio deployments._ ## Similar posts on daily.dev - [Announcing Istio 1.28.8](https://daily.dev/posts/announcing-istio-1-28-8-epijyju4g) · Istio · 0 upvotes · 0 comments - [Istio / ISTIO-SECURITY-2026-005](https://daily.dev/posts/istio-istio-security-2026-005-1tnumumha) · Istio · 0 upvotes · 0 comments - [Announcing Istio 1.28.5](https://daily.dev/posts/announcing-istio-1-28-5-0qe49rxa7) · Istio · 1 upvotes · 0 comments - [Announcing Istio 1.29.5](https://daily.dev/posts/announcing-istio-1-29-5-gj4qcmivr) · Istio · 0 upvotes · 0 comments - [Announcing Istio 1.29.4](https://daily.dev/posts/announcing-istio-1-29-4-nbqrye7ll) · Istio · 0 upvotes · 0 comments --- Tags: [#security](https://daily.dev/tags/security), [#microservices](https://daily.dev/tags/microservices), [#istio](https://daily.dev/tags/istio), [#service-mesh](https://daily.dev/tags/service-mesh), [#envoy](https://daily.dev/tags/envoy) [View this post on daily.dev](https://daily.dev/posts/announcing-istio-1-28-9-jnb76bnms) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Announcing Istio 1.28.9","url":"https://daily.dev/posts/announcing-istio-1-28-9-jnb76bnms","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/announcing-istio-1-28-9-jnb76bnms"},"datePublished":"2026-06-24T18:25:42.324Z","dateModified":"2026-09-13T20:01:41.849Z","description":"Istio 1.28.9 is a patch release focused entirely on security fixes. 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