CVE-2026-111809: Apache Traffic Server: HEAD requests carrying Content-Length or Transfer-Encoding enable request smuggling
Vulnerability summary
CVE-2026-111809 is a critical (CVSS 9.3) vulnerability in apache software foundation apache traffic server. EPSS estimates a 0.22% chance of exploitation in the next 30 days, higher than 12.3% of scored vulnerabilities.
Not severe (CVSS 6.9, network access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Timeline
- 21-10-2026PublishedVulnerability first disclosed.
- 28-10-2026Last modifiedVulnerability information updated.
Description
Apache Traffic Server allows request smuggling via HEAD requests that carry Content-Length or Transfer-Encoding. This issue affects Apache Traffic Server: from 8.0.0 through 8.1.11, from 9.0.0 through 9.2.15, from 10.0.0 through 10.1.4, 10.2.0. Users are recommended to upgrade to version 9.2.16, 10.1.5, or 10.2.1, which fix the issue.
CVSS metrics
7 scores · 4 sources · 2 versions- NVDNIST6.9MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- OSV · DebianEcosystem advisory · calculated6.9MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- OSV · UbuntuEcosystem advisory · calculated6.9MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:H/SA:N
- NVDNIST9.3CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N
- OSV · UbuntuEcosystem advisory · calculated9.3CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N
EPSS trend
Probability
0.22%
Chance of exploitation in the next 30 days
Percentile
12%
Versus all other CVEs
30-day change
Change unavailable
Change unavailable
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
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.
Apache software foundation1 product
- apache traffic server≥ 8.0.0, ≤ 8.1.11 | ≥ 9.0.0, ≤ 9.2.15 | ≥ 10.0.0, ≤ 10.1.4 | 10.2.0
Debian1 product
- trafficserverAll versions (No fix recorded)
Ubuntu1 product
- trafficserverAll versions (No fix recorded)
3 vendors · 3 products
References
5 links- lists.apache.org/thread/r95dq29ywcd1f4x30snxlqmb12z4s4kcVendor Advisory
