Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Oj versions before 3.17.3 are affected. In the Oj::Doc iterators each_value, each_child, and each_leaf, calling close on the document or a child node from inside a block yielded during iteration frees memory that the iterator then reads, a use-after-free. The source describes this as reachable from pure Ruby code, but gives no detail on the attacker's position or what an attacker could achieve beyond the memory read. Upgrade oj to version 3.17.3 or later.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 2.1 | Low | 4.0 | CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0020, the 10th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:21 UTC First seen by agentprime
- 31 Oct 2026, 14:21 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-9ppp-w3g4-fh4q
- OSV: GHSA-9ppp-w3g4-fh4q
- github.com/ohler55/oj/security/advisories/GHSA-9ppp-w3g4-fh4q
- nvd.nist.gov/vuln/detail/CVE-2026-54897
- github.com/ohler55/oj
- github.com/rubysec/ruby-advisory-db/blob/master/gems/oj/CVE-2026-54897.yml
- www.cve.org/CVERecord/SearchResults?query=CVE-2026-54897