CVE-2026-33811: Crash when handling long CNAME response in net
Vulnerability summary
CVE-2026-33811 is a high (CVSS 7.5) Double Free vulnerability in go standard library net. EPSS estimates a 0.88% chance of exploitation in the next 30 days, higher than 59% of scored vulnerabilities.
Severe, CVSS 7.5 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 1% (FIRST, 03-11-2026)
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 57 · Related 58Timeline
- 07-05-2026PublishedVulnerability first disclosed.
- 18-09-2026Last modifiedVulnerability information updated.
Description
When using LookupCNAME with the cgo DNS resolver, a very long CNAME response can trigger a double-free of C memory and a crash.
CVSS metrics
8 scores · 8 sources · 1 version- OSV · Red hatEcosystem 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 · WolfiEcosystem 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
- OSV · AlpineEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.88%
Chance of exploitation in the next 30 days
Percentile
59%
Versus all other CVEs
30-day change
Increase +0.06 pp
From 0.81% on 04-10-2026
Known exploited
Compare KEV catalogsNot in the CISA KEV catalog.
Not in the ENISA CNW catalog.
Not in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Chainguard198 products
- aactl< 0.4.12-r51 | < 0.4.12-r50
- actAll versions (No fix recorded)
- actions-runner-controller-fips< 0.14.1-r2 | < 0.14.1-r1 | All versions (No fix recorded)
- addon-resizerAll versions (No fix recorded)
- addon-resizer-fipsAll versions (No fix recorded)
Alpine2 products
- go≥ 1.26.0, < 1.25.10-r0 | ≥ 1.26.0, < 1.26.3-r0
- rclone< 1.74.1-r0
2 vendors · 200 products · Showing 200 of 3391
References
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