CVE-2020-26243
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…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (2.66%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 2.66% probability · 85th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-20, CWE-119
- Affected
- nanopb project/nanopb
- Source
- security-advisories@github.com
References
- https://github.com/nanopb/nanopb/blob/2b48a361786dfb1f63d229840217a93aae064667/CHANGELOG.txtRelease Notes, Third Party Advisory
- https://github.com/nanopb/nanopb/commit/4fe23595732b6f1254cfc11a9b8d6da900b55b0cPatch, Third Party Advisory
- https://github.com/nanopb/nanopb/issues/615Exploit, Patch, Third Party Advisory
- https://github.com/nanopb/nanopb/security/advisories/GHSA-85rr-4rh9-hhwhThird Party Advisory
- https://github.com/nanopb/nanopb/blob/2b48a361786dfb1f63d229840217a93aae064667/CHANGELOG.txtRelease Notes, Third Party Advisory
- https://github.com/nanopb/nanopb/commit/4fe23595732b6f1254cfc11a9b8d6da900b55b0cPatch, Third Party Advisory
- https://github.com/nanopb/nanopb/issues/615Exploit, Patch, Third Party Advisory
- https://github.com/nanopb/nanopb/security/advisories/GHSA-85rr-4rh9-hhwhThird Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.