CVE-2026-11352: QUIC zero-length UDP datagrams busy-loop
Vulnerability summary
CVE-2026-11352 is a high (CVSS 7.5) Loop with Unreachable Exit Condition vulnerability in curl. EPSS estimates a 1.01% chance of exploitation in the next 30 days, higher than 63.1% of scored vulnerabilities. 1 public exploit is recorded.
Public exploit (reference, Date unknown)
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 5 · Related 5Timeline
- 03-07-2026PublishedVulnerability first disclosed.
- 15-09-2026Last modifiedVulnerability information updated.
Description
An issue in curl’s QUIC UDP receive function allows a malicious HTTP/3 server to trigger a remote denial of service against a curl or libcurl client. Because the helper function discards zero-length UDP datagrams before counting them toward the per-call packet budget, a connected QUIC peer can continuously stream empty datagrams to indefinitely stall the client.
CVSS metrics
6 scores · 6 sources · 1 version- OSV · AlpineEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · ChainguardEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- NVDNIST7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
1.01%
Chance of exploitation in the next 30 days
Percentile
63%
Versus all other CVEs
30-day change
Increase +0.29 pp
From 0.71% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
1 foundExploit Reference (hackerone.com)
Maturity: unknown
Weaknesses
CWE · root causeAffected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Chainguard10 products
- eco-python-curl< 8.21.0-r0
- eco-python-curl-minimal< 8.21.0-r0
- eco-python-curl-minimal-bin< 8.21.0-r0
- eco-python-curl-minimal-dev< 8.21.0-r0
- eco-python-curl-minimal-doc< 8.21.0-r0
Alpine1 product
- curl≥ 8.18.0, < 8.22.0-r0 | ≥ 8.18.0, < 8.21.0-r0
Curl1 product
- curl≥ 8.18.0, < 8.20.1 | ≥ 6a3d0b6d631d5e9bec797306b5b41a9f440a088d, < 56eca2afb4806f1032872fa97d1834b3c1385276 | 8.20.0 | 8.19.0 | 8.18.0
Debian1 product
- curl< 8.21.0~rc2-1
Haxx1 product
- curl≥ 8.18.0, < 8.21.0
Ubuntu1 product
- curl< 8.18.0-1ubuntu2.3
6 vendors · 15 products
