How severe is CVE-2021-3907?

CVE-2021-3907 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.

Is CVE-2021-3907 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (89th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3907?

CVE-2021-3907 primarily affects Cloudflare Octorpki. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-3907?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-3907 published?

CVE-2021-3907 was published on 2021-11-11 and last updated on 2026-06-17.

CVE-2021-3907

CVE-2021-3907 is a high-severity vulnerability in Cloudflare Octorpki with a CVSS 3.x base score of 7.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-22.

Key facts

Severity: High (CVSS 3.x base score 7.4)
CVSS v2: 7.5
EPSS exploit prediction: 4% (89th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-22
Affected product: Cloudflare Octorpki
Published: 2021-11-11
Last modified: 2026-06-17

Description

OctoRPKI does not escape a URI with a filename containing "..", this allows a repository to create a file, (ex. rsync://example.org/repo/../../etc/cron.daily/evil.roa), which would then be written to disk outside the base cache folder. This could allow for remote code execution on the host machine OctoRPKI is running on.

Frequently asked questions

What is CVE-2021-3907?: OctoRPKI does not escape a URI with a filename containing "..", this allows a repository to create a file, (ex. rsync://example.org/repo/../../etc/cron.daily/evil.roa), which would then be written to disk outside the base cache folder. This could allow for remote code execution on the host machine OctoRPKI is running on.
How severe is CVE-2021-3907?: CVE-2021-3907 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.
Is CVE-2021-3907 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (89th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3907?: CVE-2021-3907 primarily affects Cloudflare Octorpki. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-3907?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-3907 published?: CVE-2021-3907 was published on 2021-11-11 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:a:cloudflare:octorpki:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

More vulnerabilities in Cloudflare Octorpki

CVE-2021-3978 — High (CVSS 7.5): When copying files with rsync, octorpki uses the "-a" flag 0, which forces rsync to copy binaries with the suid bit set…
CVE-2021-3761 — High (CVSS 7.5): Any CA issuer in the RPKI can trick OctoRPKI prior to 1.3.0 into emitting an invalid VRP "MaxLength" value, causing RTR…
CVE-2021-3908 — Medium (CVSS 5.9): OctoRPKI does not limit the depth of a certificate chain, allowing for a CA to create children in an ad-hoc fashion,…
CVE-2022-3616 — Medium (CVSS 5.4): Attackers can create long chains of CAs that would lead to OctoRPKI exceeding its max iterations parameter. In…
CVE-2021-3910 — Medium (CVSS 4.4): OctoRPKI crashes when encountering a repository that returns an invalid ROA (just an encoded NUL (\0) character).
CVE-2021-3909 — Medium (CVSS 4.4): OctoRPKI does not limit the length of a connection, allowing for a slowloris DOS attack to take place which makes…

All CVEs affecting Cloudflare Octorpki →

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