Buffer overflow in Nanopb
CVE-2020-26243
Nanopb is a small code-size Protocol Buffers implementation. In Nanopb before versions 0.4.4 and 0.3.9.7, decoding specifically formed message can leak memory if dynamic allocation is enabled and an oneof field contains a static submessage that contains a dynamic field, and the message being decoded contains the submessage multiple times. This is rare in normal messages, but it is a concern when untrusted data is parsed. This is fixed in versions 0.3.9.7 and 0.4.4. The following workarounds are available: 1) Set the option `no_unions` for the oneof field. This will generate fields as separate instead of C union, and avoids triggering the problematic code. 2) Set the type of the submessage field inside oneof to `FT_POINTER`. This way the whole submessage will be dynamically allocated and the problematic code is not executed. 3) Use an arena allocator for nanopb, to make sure all memory can be released afterwards.
Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.027 (85.2th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 85th percentile — 85.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.027 · newest: 0.027 · change: 0.000
Affected products
- Nanopb — versions < 0.3.9.7, >= 0.4.0, < 0.4.4
- Nanopb Project
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/nanopb/nanopb/security/advisories/GHSA-85rr-4rh9-hhwh (Third Party Advisory)
- github.com/nanopb/nanopb/issues/615 (Exploit, Patch, Third Party Advisory)
- github.com/nanopb/nanopb/commit/4fe23595732b6f1254cfc11a9b8d6da900b55b0c (Patch, Third Party Advisory)
- github.com/nanopb/nanopb/blob/2b48a361786dfb1f63d229840217a93aae064667/CHANGELO… (Third Party Advisory, Release Notes)
Frequently asked questions
- What is CVE-2020-26243?
- CVE-2020-26243 is a high-severity vulnerability in Nanopb, classified under Improper Input Validation. CVSS score: 7.5/10. Published 2020-11-25.
- How severe is CVE-2020-26243?
- High severity. CVSS v3 base score is 7.5 out of 10.
- Is CVE-2020-26243 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.