CVE-2026-2836
Cloudflare Pingora ≤ 0.8.0
Raw vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:H/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:XSummary
CVE-2026-2836 is a high-severity Insufficient Verification of Data Authenticity (CWE-345) vulnerability in Cloudflare Pingora. Its CVSS base score is 8.4 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Mark-of-the-Web Bypass (T1553.005); ranked at the 32th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SC-23 (Session Authenticity) and SI-7 (Software, Firmware, and Information Integrity) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-2836 is a cache poisoning vulnerability in the Pingora HTTP proxy framework’s default cache key construction, published on 2026-03-05. The default HTTP cache key implementation generates keys using only the URI path, excluding critical factors such as the host header (authority). This affects users of Pingora's alpha proxy caching feature who rely on the default CacheKey implementation, potentially leading to improper serving of cross-origin responses.
The vulnerability has a CVSS score of 8.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N) and is associated with CWE-345. Remote attackers require no privileges but need user interaction to exploit it over the network with low complexity. Successful exploitation enables cross-tenant data leakage in multi-tenant deployments, where attackers poison the cache so users from one tenant receive cached responses from another, or cache poisoning attacks to serve malicious content to legitimate users.
Advisories recommend upgrading to Pingora v0.8.0 or higher, which removes the insecure default cache key implementation; users must then explicitly implement their own callback including the Host header (authority), origin server HTTP scheme, and other relevant attributes. On previous versions, users should remove any default CacheKey usage and implement a custom one that includes at minimum the host header/authority and upstream peer’s HTTP scheme. See the Pingora GitHub repository at https://github.com/cloudflare/pingora for details.
Cloudflare's CDN infrastructure was not affected, as its default cache key implementation uses multiple factors to prevent such poisoning and never relied on the provided default.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-9512
Vulnerability Data
A cache poisoning vulnerability has been found in the Pingora HTTP proxy framework’s default cache key construction. The issue occurs because the default HTTP cache key implementation generates cache keys using only the URI path, excluding critical factors such as…
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the host header (authority). Operators relying on the default are vulnerable to cache poisoning, and cross-origin responses may be improperly served to users. Impact This vulnerability affects users of Pingora's alpha proxy caching feature who relied on the default CacheKey implementation. An attacker could exploit this for: * Cross-tenant data leakage: In multi-tenant deployments, poison the cache so that users from one tenant receive cached responses from another tenant * Cache poisoning attacks: Serve malicious content to legitimate users by poisoning shared cache entries Cloudflare's CDN infrastructure was not affected by this vulnerability, as Cloudflare's default cache key implementation uses multiple factors to prevent cache key poisoning and never made use of the previously provided default. Mitigation: We strongly recommend Pingora users to upgrade to Pingora v0.8.0 or higher, which removes the insecure default cache key implementation. Users must now explicitly implement their own callback that includes appropriate factors such as Host header, origin server HTTP scheme, and other attributes their cache should vary on. Pingora users on previous versions may also remove any of their default CacheKey usage and implement their own that should at minimum include the host header / authority and upstream peer’s HTTP scheme.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 8 hardening rules · 5 OS baselines
V3.5.5
Mitigating Controls (NIST 800-53 r5) AI
Explicit requirement to protect session authenticity structurally prevents the weakness for communications.
Integrity verification tools detect (but do not stop) the acceptance of data lacking authenticity.
Cryptographic mechanisms can be used to verify authenticity, thereby preventing acceptance of invalid data.
Associating security attributes with exchanged information supports verification of authenticity.
Integrity protection on transmitted data directly stops acceptance of unauthenticated or altered data.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
CWE-345 directly impairs RC.RP-05's verification of restored-asset integrity/authenticity, largely defeating the outcome while still leaving other restoration-confirmation steps partially viable.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect missing or weak data authenticity verification.
Network controls can enforce authenticated channels, reducing risk of accepting unauthentic data.
Secure network services often include authenticity checks for data exchanged over those services.
Cryptographic mechanisms directly verify data origin and integrity, preventing acceptance of unauthentic data.
Secure SDLC incorporates authenticity verification requirements throughout development.
Application security requirements can mandate data authenticity verification mechanisms.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Oracle Linux 8 (2 rules)
- V-248574 YUM must be configured to prevent the installation of patches, service packs, device drivers, or OL 8 system components that have not been digitally signed using a certificate that is recognized and approved by the organization. prevents CWE-345
- V-248575 OL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
Oracle Linux 9 (1 rule)
- V-271525 OL 9 must have GPG signature verification enabled for all software repositories. prevents CWE-345
RHEL 7 (2 rules)
- V-204447 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
- V-204448 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
RHEL 8 (2 rules)
- V-230264 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
- V-230265 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
RHEL 9 (1 rule)
- V-257822 RHEL 9 must have GPG signature verification enabled for all software repositories. prevents CWE-345