- Exploited
- No known exploitation
- Fix
- Fixed in 0.11.19
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 0.11.19.
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 20/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
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.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original 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.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure?/25Unknown. No advisory context yet
- Reach20/20quinn-proto: 11.8M downloads a week
- Severity?/10Unknown. No CVSS score or vendor rating
- No patch0/5No signal
What would change the score
- Would score about 75 if added to CISA KEV
- Would score about 70 if CISA's SSVC rates exploitation active
- Would score about 42 if advisories confirm default setups are exposed
Impact
- Widely used
quinn-proto has 11.8m weekly downloads.Source: crates.io
What to do
Upgrade to a fixed version: 0.11.19.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
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"}.Timeline
- Advisory published44 days
- Record last updated
Affected versions
- quinn-protocrates.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.
Evidence 6
Other links · 6
- Advisory
- Repository
- Repository
- Repository
- Repository
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about RUSTSEC-2026-0524
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: cve.now feed data
Which versions are affected by RUSTSEC-2026-0524?
quinn-proto (crates.io): from 0.11.0 before 0.11.19.Source: cve.now feed data
How do I fix RUSTSEC-2026-0524?
Upgrade to a fixed version: 0.11.19.Source: cve.now feed data