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CVE-2020-26243

24
FAUCET Score

CVE-2020-26243 describes a memory leak vulnerability in Nanopb, a Protocol Buffers implementation, affecting versions prior to 0.4.4 and 0.3.9.7. Specifically crafted messages can cause memory leaks when dynamic allocation is enabled and certain conditions involving oneof fields and static submessages with dynamic fields are met. This vulnerability has a CVSS score of 7.5 (High), indicating it can be exploited remotely with low attack complexity, leading to high availability impact. While there are no known public exploits, Metasploit modules, or Nuclei templates, and minimal community discussion, the issue is addressed in updated Nanopb versions and has several workarounds.

Impacted Technologies

VendorProductVersion(s)CPE
< 0.3.9.7CPE matchmatch criteria
cpe:2.3:a:nanopb_project:nanopb:*:*:*:*:*:*:*:*
>= 0.4.0, < 0.4.4CPE matchmatch criteria
cpe:2.3:a:nanopb_project:nanopb:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.61%
Probability of exploitation in next 30 days
EPSS Percentile
83.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0261 is in the 71st percentile among its peer group of 51,485 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (4)

github_advisorypatch availablevia nvd_reference
View patch
pippatch availablevia ghsa
Product: nanopbFixed in: 0.3.9.7
pippatch availablevia ghsa
Product: nanopbFixed in: 0.4.4
redhatend of lifevia redhat_api
Product: OpenShift Service Mesh 1Fixed in: servicemesh-proxy

Vendor Advisories (2)

pipGHSA-85rr-4rh9-hhwhmedium

Memory leak in Nanopb

Nov 25, 2020
redhatCVE-2020-26243Important

nanopb: oneof fields with PB_ENABLE_MALLOC can leak memory

Nov 25, 2020

References

github.com / nanopb/nanopb/blob/2b48a361786dfb1f63d229840217a93aae064667/CHANGELOG.txt
Release NotesThird Party Advisory
github.com / nanopb/nanopb/commit/4fe23595732b6f1254cfc11a9b8d6da900b55b0c
PatchThird Party Advisory
github.com / nanopb/nanopb/issues/615
ExploitPatchThird Party Advisory
github.com / nanopb/nanopb/security/advisories/GHSA-85rr-4rh9-hhwh
Third Party Advisory