high CVSS 7.1

CVE-2021-47240·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: net: qrtr: fix OOB Read in qrtr_endpoint_post Syzbot reported slab-out-of-bounds Read in qrtr_endpoint_post. The problem was in wrong _size_ type: if (len != ALIGN(size, 4) + hdrlen) goto err; If size from qrtr_hdr is 4294967293 (0xfffffffd), the result of ALIGN(size, 4) will be 0. In case of len == hdrlen and size == 4294967293 in header this check won't fail and skb_put_data(skb, data + hdrlen, size); will read out of bound from data, which is hdrlen allocated block.

Severity
high
Software
Kernel
Fixed in
5.12.13
Published
2024-05-21

Affected versions

From: 5.11

Until: 5.12.13

Fixed in: 5.12.13

How to fix this CVE

Update your Linux kernel to version 5.12.13 or later to patch an out-of-bounds read vulnerability in the QRTR (Qualcomm IPC Router) networking subsystem. This vulnerability could allow a local, privileged attacker to read sensitive kernel memory. Systems running kernel versions 5.11 through 5.12.12 should prioritize this update.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check your kernel version with `uname -r` and verify if it falls between 5.11 and 5.12.12
  2. Step 2: Confirm QRTR module is loaded by running `lsmod | grep qrtr` (if present, the component is active)
  3. Step 3: Search kernel logs for qrtr-related errors using `dmesg | grep qrtr` or `journalctl -g qrtr`
  4. Step 4: After patching, verify the new kernel version with `uname -r` and confirm it is 5.12.13 or later

FAQ

What is CVE-2021-47240?

CVE-2021-47240 is an out-of-bounds memory read vulnerability in the Linux kernel's QRTR (Qualcomm IPC Router) networking driver. An attacker with local privileges can craft a malicious packet with an oversized size field that bypasses length validation, allowing unauthorized kernel memory to be read.

Is CVE-2021-47240 being actively exploited?

No, CVE-2021-47240 is not listed as actively exploited according to CISA's Known Exploited Vulnerabilities catalog, and no public exploits are currently available.

What versions of Kernel are affected by CVE-2021-47240?

Linux kernel versions 5.11 through 5.12.12 are vulnerable. Version 5.12.13 and later contain the fix.

How do I check if my server is vulnerable to CVE-2021-47240?

Run `uname -r` to check your kernel version. If it shows any version from 5.11.x through 5.12.12, your system is vulnerable and requires an immediate kernel update.

Does Defensia detect CVE-2021-47240?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Linux kernel is installed on a monitored server, CVE-2021-47240 will appear in your dashboard with remediation steps.

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CVE-2026-43501CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: ipv6: rpl: reserve mac_len headroom when recompressed SRH grows ipv6_rpl_srh_rcv() decompresses an RFC 6554 Source Routing Header, swaps the next segment into ipv6_hdr->daddr, recompresses, then pulls the old header and pushes the new one plus the IPv6 header back. The recompressed header can be larger than the received one when the swap reduces the common-prefix length the segments share with daddr (CmprI=0, CmprE>0, seg[0][0] != daddr[0] gives the maximum +8 bytes). pskb_expand_head() was gated on segments_left == 0, so on earlier segments the push consumed unchecked headroom. Once skb_push() leaves fewer than skb->mac_len bytes in front of data, skb_mac_header_rebuild()'s call to: skb_set_mac_header(skb, -skb->mac_len); will store (data - head) - mac_len into the u16 mac_header field, which wraps to ~65530, and the following memmove() writes mac_len bytes ~64KiB past skb->head. A single AF_INET6/SOCK_RAW/IPV6_HDRINCL packet over lo with a two segment type-3 SRH (CmprI=0, CmprE=15) reaches headroom 8 after one pass; KASAN reports a 14-byte OOB write in ipv6_rthdr_rcv. Fix this by expanding the head whenever the remaining room is less than the push size plus mac_len, and request that much extra so the rebuilt MAC header fits afterwards.
CVE-2026-64216CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: netfs: Fix potential UAF in netfs_unlock_abandoned_read_pages() netfs_unlock_abandoned_read_pages(rreq) accesses the index of the folios it is wanting to unlock and compares that to rreq->no_unlock_folio so that it doesn't unlock a folio being read for netfs_perform_write() or netfs_write_begin(). However, given that netfs_unlock_abandoned_read_pages() is called _after_ NETFS_RREQ_IN_PROGRESS is cleared, the one folio that it's not allowed to dereference is the one specified by ->no_unlock_folio as ownership immediately reverts to the caller. Fix this by storing the folio pointer instead and using that rather than the index. Also fix netfs_unlock_read_folio() where the same applies.

References

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