CVE-2021-47515

Advisory lineage Upstream: 0 Downstream: 6
Analyzed
Published: 24 May 2024, 15:09
Last modified:23 May 2026, 15:20

Vulnerability Summary

Overall Risk (default)
low
22/100
CVSS Score
5.5 MEDIUM
v3.1 (nvd)
EPSS Score
0.01% LOW
0% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

24 May 2024, 15:09
Published
Vulnerability first disclosed
23 May 2026, 15:20
Last Modified
Vulnerability information updated

Description

In the Linux kernel, the following vulnerability has been resolved: seg6: fix the iif in the IPv6 socket control block When an IPv4 packet is received, the ip_rcv_core(...) sets the receiving interface index into the IPv4 socket control block (v5.16-rc4, net/ipv4/ip_input.c line 510): IPCB(skb)->iif = skb->skb_iif; If that IPv4 packet is meant to be encapsulated in an outer IPv6+SRH header, the seg6_do_srh_encap(...) performs the required encapsulation. In this case, the seg6_do_srh_encap function clears the IPv6 socket control block (v5.16-rc4 net/ipv6/seg6_iptunnel.c line 163): memset(IP6CB(skb), 0, sizeof(*IP6CB(skb))); The memset(...) was introduced in commit ef489749aae5 ("ipv6: sr: clear IP6CB(skb) on SRH ip4ip6 encapsulation") a long time ago (2019-01-29). Since the IPv6 socket control block and the IPv4 socket control block share the same memory area (skb->cb), the receiving interface index info is lost (IP6CB(skb)->iif is set to zero). As a side effect, that condition triggers a NULL pointer dereference if commit 0857d6f8c759 ("ipv6: When forwarding count rx stats on the orig netdev") is applied. To fix that issue, we set the IP6CB(skb)->iif with the index of the receiving interface once again.

CVSS Metrics

  • v3.1•MEDIUM•Score: 5.5CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Trends

Current EPSS score: 0.01%• Percentile: 3%

Techniques & Countermeasures

  • CWE-476•NULL Pointer Dereference

    The product dereferences a pointer that it expects to be valid but is NULL.

Affected Systems

  • linux•linux

    ≥ c630ec8bdadae9d557b1ceb9d6c06e149108a0d4, < b16d412e5f79734033df04e97d7ea2f50a8e9fe3 | ≥ 2f704348c93ff8119e642dae6a72327f90b82810, < 6431e71093f3da586a00c6d931481ffb0dc2db0e | ≥ ef489749aae508e6f17886775c075f12ff919fb1, < ef8804e47c0a44ae106ead1740408af5ea6c6ee9 | ≥ ef489749aae508e6f17886775c075f12ff919fb1, < 666521b3852d2b2f52d570f9122b1e4b50d96831 | ≥ ef489749aae508e6f17886775c075f12ff919fb1, < 98adb2bbfa407c9290bda299d4c6f7a1c4ebd5e1 | ≥ ef489749aae508e6f17886775c075f12ff919fb1, < ae68d93354e5bf5191ee673982251864ea24dd5c | b71b7e0280f47b4ac633fbfd153423814ea87810 | ≥ 4.14.98, < 4.14.258 | ≥ 4.19.20, < 4.19.221 | ≥ 4.20.7, < 4.21 | 5.0

  • linux•linux_kernel

    ≥ 4.14.98, < 4.14.258 | ≥ 4.19.20, < 4.19.221 | ≥ 4.20.7, < 5.0 | ≥ 5.0.1, < 5.4.165 | ≥ 5.5, < 5.10.85 | ≥ 5.11, < 5.15.8 | 5.0 | 5.0:rc6 | 5.0:rc7 | 5.0:rc8 | 5.16:rc1 | 5.16:rc2 | 5.16:rc3 | 5.16:rc4

References (6)