CVE-2023-32731 | Information leak in gRPC

When gRPC HTTP2 stack raised a header size exceeded error, it skipped parsing the rest of the HPACK frame. This caused any HPACK table mutations to also be skipped, resulting in a desynchronization of HPACK tables between sender and receiver. If leveraged, say, between a proxy and a backend, this could lead to requests from the proxy being interpreted as containing headers from different proxy clients - leading to an information leak that can be used for privilege escalation or data exfiltration. We recommend upgrading beyond the commit contained in  https://github.com/grpc/grpc/pull/33005 https://github.com/grpc/grpc/pull/33005

Published: 2023-06-09 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-32731 is rated Moderate Risk (43.6/100): CVSS High severity, with low exploitation likelihood (EPSS 0.50%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-32731

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.11% 0.50% +0.39%
2 2025-03-17 0.16% 0.11% -0.05%
3 2024-05-09 — 0.16% —

Full EPSS history (4 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-32731

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.4 3.1 HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 5.2 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2023-32731

GitHub Security Advisory for CVE-2023-32731

OS Trackers for CVE-2023-32731

vendor priority summary link
alpine high CVE-2023-32731: 1 source package rows (grpc); 1 state rows across 1 repos (3.18-community); fixed 0, open 1. https://security.alpinelinux.org/vuln/CVE-2023-32731
debian unimportant CVE-2023-32731 unimportant priority: Debian including 1 source packages (grpc), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2023-32731
redhat medium — https://access.redhat.com/security/cve/CVE-2023-32731
suse high CVE-2023-32731 severity important: SUSE including 54 source package names (abseil-cpp-devel-20230802.1-150400.10.4.1, grpc, …), 286 product×package rows across 45 product lines (Image SLES15-SP4-BYOS-Azure, Image SLES15-SP4-HPC-BYOS-Azure, … (45 product lines)): Fixed 210, Known Not Affected 72, First Fixed 4. https://www.suse.com/security/cve/CVE-2023-32731/
ubuntu medium CVE-2023-32731 medium priority: Ubuntu including 1 source packages (grpc), 13 status rows across 13 suites (bionic, focal, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): needs-triage 6, ignored 5, DNE 1, released 1. https://ubuntu.com/security/CVE-2023-32731

Affected software / configurations for CVE-2023-32731

Vendor Product Version Raw CPE
grpc grpc >= 1.53.0, < 1.55.0 cpe:2.3:a:grpc:grpc:*:*:*:*:*:*:*:*

References for CVE-2023-32731

cvelogic Threat Intelligence