CVE-2026-33215: linuxfoundation nats-server Improper Authentication
CVSS: 6.5v3.1MediumAnalyzed
AliasesUBUNTU-CVE-2026-33215DEBIAN-CVE-2026-33215CGA-2x2g-7mmc-7mccCGA-45rq-x3jv-6wgqCGA-4v9r-v8v4-5j49CGA-4xxr-c862-xfmfCGA-5gvq-42m6-c39gCGA-62vv-vjg8-p5g4CGA-67fr-vvgx-h97pCGA-6gxc-25m3-4rjqCGA-6wv4-prw2-wp84CGA-7pc2-5336-c8fxCGA-8j25-6pq3-vjm8CGA-8q6j-47wm-rvf3CGA-9vq5-fjxm-6627CGA-f2qx-f3x9-j3h2CGA-ff98-m9xg-mj5pCGA-ggr7-93wp-7jr8CGA-gjr3-prj6-4x64CGA-gmjc-7pgg-hq35CGA-hqqc-46j2-4jwgCGA-j7qq-cr44-3pq9CGA-m35f-rf7g-q6rvCGA-mpwc-c5m8-rpqfCGA-pcxx-hrh4-c7w7CGA-prcf-5qmv-fxcqGHSA-fcjp-h8cc-6879BIT-nats-2026-33215GO-2026-4833CGA-2622-r698-374rCGA-2pfj-78pq-x2q2CGA-33g5-cr53-fwmrCGA-3g5v-6m2p-2ffrCGA-529m-7456-p4mjCGA-584x-hpxc-7jjjCGA-5h46-8m38-g7rhCGA-68c2-4m8j-xfv9CGA-6wq2-pqqq-m8f7CGA-775f-x8v4-354vCGA-78rx-8mpj-mq76CGA-7wfp-fvcw-7vf9CGA-87xq-f566-47f5CGA-cqw7-w8cx-m333CGA-cvwx-6gpp-846pCGA-h3vv-xf6c-g9h5CGA-hcx2-xq8w-4cwwCGA-hwjq-xc75-cfpgCGA-jfww-ppgh-vhp9CGA-mg89-fmr6-6cqhCGA-p393-5hc7-5cfhCGA-p4mv-fcxr-cmhxCGA-p6w8-8fqh-cp6gCGA-q2w6-929h-x8v8CGA-q7q6-463r-j75gCGA-r8vg-3rw5-w8vvCGA-rm64-2wh4-v9xfCGA-rqj3-fvx3-88v3CGA-v92q-jrqq-j5p2CGA-vwxc-2453-x65pCGA-wqhw-9hv4-7pwmCGA-wqp7-r2gc-8m87
Published 24-03-2026Last modified 25-03-2026
Vulnerability summary
CVE-2026-33215 is a medium (CVSS 6.5) Improper Authentication vulnerability in linuxfoundation nats-server. EPSS estimates a 0.28% chance of exploitation in the next 30 days, higher than 19.3% of scored vulnerabilities.
CVSS score
6.5/10
010
Medium · v3.1 (CVE.org)EPSS score
0.28%
0%100%
Low · +0.04 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 2 · Related 3Timeline
- 24-03-2026PublishedVulnerability first disclosed.
- 25-03-2026Last modifiedVulnerability information updated.
Description
NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server provides an MQTT client interface. Prior to versions 2.11.15 and 2.12.5, Sessions and Messages can by hijacked via MQTT Client ID malfeasance. Versions 2.11.15 and 2.12.5 patch the issue. No known workarounds are available.
CVSS metrics
7 scores · 7 sources · 1 versionMedium 6.5Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:LSourcesAll 7 agree
- OSV · UbuntuEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
- OSV · DebianEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
- OSV · WolfiEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:L
- OSV · GoEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:L
- OSV · ChainguardEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:L
- NVDNIST6.5MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
EPSS trend
Probability
0.28%
Chance of exploitation in the next 30 days
Percentile
19%
Versus all other CVEs
30-day change
+0.04 pp
From 0.24% on 19-09-2026
19-09-202619-10-2026
EPSS score0.28%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-287Improper AuthenticationWhen an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
- CWE-488Exposure of Data Element to Wrong SessionThe product does not sufficiently enforce boundaries between the states of different sessions, causing data to be provided to, or used by, the wrong session.
Affected systems
Chainguard28 products
- k3s< 1.35.2.1-r4
- k3s-1.32< 1.32.13.1-r7
- k3s-1.33< 1.33.9.1-r6
- k3s-static< 1.35.2.1-r4
- k3s-static-1.32< 1.32.13.1-r7
Wolfi12 products
- k3s< 1.35.2.1-r4
- k3s-1.32< 1.32.13.1-r7
- k3s-1.33< 1.33.9.1-r6
- k3s-static< 1.35.2.1-r4
- k3s-static-1.32< 1.32.13.1-r7
Debian1 product
- nats-serverAll versions (No fix recorded) | < 2.12.6-1
Github.com/nats-io1 product
- nats-serverAll versions (No fix recorded)
Github.com/nats-io/nats-server1 product
- v2< 2.11.15 | ≥ 2.12.0-RC.1, < 2.12.6
Linuxfoundation1 product
- nats-server≥ 2.0.0, < 2.11.15 | ≥ 2.12.0, < 2.12.5
Nats-io1 product
- nats-server< 2.11.15 | ≥ 2.12.0-RC.1, < 2.12.6
Ubuntu1 product
- nats-serverAll versions (No fix recorded)
8 vendors · 46 products
References
10 links- github.com/nats-io/nats-server/security/advisories/GHSA-fcjp-h8cc-6879X Refsource CONFIRMREPORTAdvisoryWEBVendor Advisory
