GHSA-xq2h-p299-vjwv CVE-2026-2833 RUSTSEC-2026-0033
Pingora vulnerable to HTTP Request Smuggling via Premature Upgrade
- Severity
- 0.0 / 10
- Critical · CVSS 4.0
- Exploit chance (EPSS)
- 0.67%
- Chance of exploitation in the next 30 days. Higher than 51.96% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
- Fix
0.8.0- Upgrade pingora-core to this version or later
Description
Impact
Pingora versions prior to 0.8.0 would immediately forward bytes following a request with an Upgrade header to the backend, without waiting for a 101 Switching Protocols response. This allows an attacker to smuggle requests to the backend and bypass proxy-level security controls.
This vulnerability primarily affects standalone Pingora deployments where a Pingora proxy is exposed to external traffic. An attacker could exploit this to bypass proxy-level ACL controls and WAF logic, poison caches and upstream connections, or perform cross-user attacks by hijacking sessions.
Note: Cloudflare customers and Cloudflare's CDN infrastructure were not affected by this vulnerability, as ingress proxies in the CDN stack maintain proper HTTP parsing boundaries and do not prematurely switch to upgraded connection forwarding mode.
Patches
Pingora users should upgrade to Pingora v0.8.0 or higher, which fixes this issue by only switching connection modes after receiving a 101 Switching Protocols response from the backend (hash 824bdeefc61e121cc8861de1b35e8e8f39026ecd). Without a 101 response, subsequent bytes continue to be parsed as HTTP requests.
Workarounds
As a workaround, users may return an error on requests with the Upgrade header present in their request filter logic in order to stop processing bytes beyond the request header and disable downstream connection reuse.
References
See CVE-2026-2833 and the Cloudflare blog post for more details.
Credits
Disclosed responsibly by Rajat Raghav (@xclow3n) through the Cloudflare Bug Bounty Program.
Affected versions
crates.io
| Package | Vulnerable | Fixed in |
|---|---|---|
| pingora-core | < 0.8.0 |
0.8.0 |
| pingora-core | >= 0.0.0-0, < 0.8.0 |
0.8.0 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
pingora-core crates.io → 0.8.0
- cargo
cargo update -p pingora-core --precise 0.8.0
Severity breakdown
CVSS 4.0 0.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:H/SI:H/SA:N
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- None
- Privileges required
- None
- User interaction
- None
- Confidentiality (vulnerable system)
- None
- Integrity (vulnerable system)
- High
- Availability (vulnerable system)
- None
- Confidentiality (subsequent systems)
- High
- Integrity (subsequent systems)
- High
- Availability (subsequent systems)
- None
CVSS 3.1 9.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- None
Weakness
CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
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 to prevent it
- Implementation: Use a web server that employs a strict HTTP parsing procedure, such as Apache [REF-433].
- Implementation: Use only SSL communication.
- Implementation: Terminate the client session after each request.
- System Configuration: Turn all pages to non-cacheable.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| RUSTSEC-2026-0388 Pingora HTTP/2 :authority and Host header mismatch enables cache poisoning and host-based access control bypass | Not rated yet | Also affects pingora-core |
| RUSTSEC-2026-0389 Pingora HTTP/2 server memory exhaustion through unbounded default header-list and concurrent-stream limits | High | Also affects pingora-core |
| GHSA-hj7x-879w-vrp7 Pingora has HTTP Request Smuggling via HTTP/1.0 and Transfer-Encoding Misparsing | Critical | Also affects pingora-core |
| GHSA-393w-9x6h-8gc7 Pingora update for MadeYouReset HTTP/2 vulnerability | High | Also affects pingora-core |
| RUSTSEC-2025-0070 Pingora MadeYouReset HTTP/2 vulnerability | High | Also affects pingora-core |
| GHSA-93c7-7xqw-w357 Pingora has a Request Smuggling Vulnerability | Medium | Also affects pingora-core |
| EEF-CVE-2026-114216 Chunk extensions accept bare LF and CR, enabling request smuggling in Bandit | Not rated yet | Same weakness, CWE-444 |
| GHSA-pqxq-w44r-73xw AIOHTTP: Pure-Python parser request smuggling | Medium | Same weakness, CWE-444 |
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