CVE-2019-20812 — An issue was discovered in the Linux kernel before 5

An issue was discovered in the Linux kernel before 5.4.7. The prb_calc_retire_blk_tmo() function in net/packet/af_packet.c can result in a denial of service (CPU consumption and soft lockup) in a certain failure case involving TPACKET_V3, aka CID-b43d1f9f7067.

01What is this vulnerability?

An issue was discovered in the Linux kernel before 5.4.7. The prb_calc_retire_blk_tmo() function in net/packet/af_packet.c can result in a denial of service (CPU consumption and soft lockup) in a certain failure case involving TPACKET_V3, aka CID-b43d1f9f7067.

02Affected products

Vendor	Product	Versions
n	a / n/a	n/a

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2020-06-03T02:43:58.000Z
• Last modified: 2024-08-05T02:53:09.399Z

09References

• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2020-06/msg00022.html
• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00008.html
• www.oracle.com — https://www.oracle.com/security-alerts/cpuApr2021.html
• git.kernel.org — https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b4…
• cdn.kernel.org — https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.4.7