https://github.com/cloudflare/pingora: Inconsistent Interpretation of HTTP Requests
CVE-2026-2835 is a critical-severity inconsistent interpretation of HTTP requests vulnerability in https://github.com/cloudflare/pingora from Cloudflare, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 0.8.0 as the first without the flaw, so updating https://github.com/cloudflare/pingora to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.89% chance of exploitation within 30 days, higher than 60% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update https://github.com/cloudflare/pingora to 0.8.0 or a later version.
- Update Pingora to 0.8.0 or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Cloudflare | https://github.com/cloudflare/pingora | before 0.8.0 | 0.8.0 |
| Cloudflare | Pingora | before 0.8.0 | 0.8.0 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 9.3 | Critical | CNA (cloudflare.com) |
| CVSS 3.1 | 9.1 | Critical | NVD |
Official description
An HTTP Request Smuggling vulnerability (CWE-444) has been found in Pingora's parsing of HTTP/1.0 and Transfer-Encoding requests. The issue occurs due to improperly allowing HTTP/1.0 request bodies to be close-delimited and incorrect handling of multiple Transfer-Encoding values, allowing attackers to send HTTP/1.0 requests in a way that would desync Pingora’s request framing from backend servers’. Impact This vulnerability primarily affects standalone Pingora deployments in front of certain backends that accept HTTP/1.0 requests. An attacker could craft a malicious payload following this request that Pingora forwards to the backend in order to: * Bypass proxy-level ACL controls and WAF logic * Poison caches and upstream connections, causing subsequent requests from legitimate users to receive responses intended for smuggled requests * Perform cross-user attacks by hijacking sessions or smuggling requests that appear to originate from the trusted proxy IP Cloudflare's CDN infrastructure was not affected by this vulnerability, as its ingress proxy layers forwarded HTTP/1.1 requests only, rejected ambiguous framing such as invalid Content-Length values, and forwarded a single Transfer-Encoding: chunked header for chunked requests. Mitigation: Pingora users should upgrade to Pingora v0.8.0 or higher that fixes this issue by correctly parsing message length headers per RFC 9112 and strictly adhering to more RFC guidelines, including that HTTP request bodies are never close-delimited. As a workaround, users can reject certain requests with an error in the request filter logic in order to stop processing bytes on the connection and disable downstream connection reuse. The user should reject any non-HTTP/1.1 request, or a request that has invalid Content-Length, multiple Transfer-Encoding headers, or Transfer-Encoding header that is not an exact “chunked” string match.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Inconsistent Interpretation of HTTP Requests
The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.
How developers prevent this class of flaw
- Use a web server that employs a strict HTTP parsing procedure, such as Apache.
- Terminate the client session after each request.
More Inconsistent Interpretation of HTTP Requests vulnerabilities (CWE-444)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in https://github.com/cloudflare/pingora
- 8.7 High severity
- 7.5 High severity
- 8.1 High severity
- 9.1 Critical severity
Recent Inconsistent Interpretation of HTTP Requests vulnerabilities
- 9.8 Critical severity
- 8.2 High severity
- 7.5 High severity
- 9.1 Critical severity
- 9.9 Critical severity
- 7.5 High severity
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