CVE-2021-40346
HIGH
7.5
CVSS Score
Published: September 8, 2021 at 04:40 PM UTC
Updated: June 17, 2026 at 04:06 AM UTC
3 products affected across 3 vendorsDebian LinuxFedoraHAProxy
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Severity
HIGH7.5
Exploit prediction
EPSS 59%
Description
An integer overflow exists in HAProxy 2.0 through 2.5 in htx_add_header that can be exploited to perform an HTTP request smuggling attack, allowing an attacker to bypass all configured http-request HAProxy ACLs and possibly other ACLs.
Affected
Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.
Debian Linux· Debiandrupal
95%2.0.0 ≤ v < 2.0.252.2.0 ≤ v < 2.2.172.3.0 ≤ v < 2.3.142.4.0 ≤ v < 2.4.42.5 dev02.5 dev12.5 dev22.5 dev32.5 dev42.5 dev52.5 dev6
Affected range stops below 2.0.25, so it looks safe — our inference, not a vendor statement
Affected range stops below 2.2.17, so it looks safe — our inference, not a vendor statement
Affected range stops below 2.3.14, so it looks safe — our inference, not a vendor statement
Affected range stops below 2.4.4, so it looks safe — our inference, not a vendor statement
Remediation
No guide yetNo remediation guidance has been written for this CVE yet. What the record does show:
Patch and advisory references
- https://git.haproxy.org/?p=haproxy.git
- https://github.com/haproxy/haproxy/commit/3b69886f7dcc3cfb3d166309018e6cfec9ce2c95
- https://jfrog.com/blog/critical-vulnerability-in-haproxy-cve-2021-40346-integer-overflow-enables-http-smuggling/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/A7V2IYO22LWVBGUNZWVKNTMDV4KINLFO/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MXTSBY2TEAXWZVFQM3CXHJFRONX7PEMN/
References (10)
x_refsource_MISCPatchThird Party Advisory
Source: [email protected]
https://github.com/haproxy/haproxy/commit/3b69886f7dcc3cfb3d166309018e6cfec9ce2c95x_refsource_MISCExploitMitigationThird Party Advisory
Source: [email protected]
https://jfrog.com/blog/critical-vulnerability-in-haproxy-cve-2021-40346-integer-overflow-enables-http-smuggling/Mailing Listx_refsource_MLIST
Source: [email protected]
https://lists.apache.org/thread.html/r284567dd7523f5823e2ce995f787ccd37b1cc4108779c50a97c79120%40%3Cdev.cloudstack.apache.org%3EMailing Listx_refsource_MLIST
Source: [email protected]
https://lists.apache.org/thread.html/r8a58fd7a29808e5d27ee56877745e58dc4bb041b9af94601554e2a5a%40%3Cdev.cloudstack.apache.org%3EVendor Advisoryx_refsource_FEDORA
Source: [email protected]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/A7V2IYO22LWVBGUNZWVKNTMDV4KINLFO/Vendor Advisoryx_refsource_FEDORA
Source: [email protected]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MXTSBY2TEAXWZVFQM3CXHJFRONX7PEMN/Vendor Advisoryx_refsource_DEBIANThird Party Advisory
Source: [email protected]
https://www.debian.org/security/2021/dsa-4968CVSS
- Attack Vector
- NETWORK
- Complexity
- LOW
- Privileges
- NONE
- User Interaction
- NONE
- Scope
- UNCHANGED
- Confidentiality
- NONE
- Integrity
- HIGH
- Availability
- NONE
Vector?
Quick Info
StatusMODIFIED
CWE
CWE-190
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