How should we interpret CVSS severity scores?

CVSS estimates technical severity, but it does not automatically equal business risk. Prioritize using context like internet exposure, asset criticality, known exploitation, and whether compensating controls exist. A Medium CVSS on an exposed production system can be more urgent than a Critical on an isolated non-production host.

Vulnerability Database

Q: What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

Q: What's the difference between a vulnerability, an exploit, and a zero-day?

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. Risk increases sharply when exploitation becomes reliable or widespread.

Q: Why do vulnerabilities keep reappearing in our environment?

Recurring findings usually come from incomplete asset discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host.

Q: How do we prioritize remediation without burning out the team?

Use a repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress so remediation is steady, not reactive.

Q: How can SynScan help reduce vulnerability risk over time?

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.

352,922

Total vulnerabilities in the database

CVE-2024-35877 — linux / linux_kernel

Missing Release of Memory after Effective Lifetime

In the Linux kernel, the following vulnerability has been resolved:

x86/mm/pat: fix VM_PAT handling in COW mappings

PAT handling won't do the right thing in COW mappings: the first PTE (or, in fact, all PTEs) can be replaced during write faults to point at anon folios. Reliably recovering the correct PFN and cachemode using follow_phys() from PTEs will not work in COW mappings.

Using follow_phys(), we might just get the address+protection of the anon folio (which is very wrong), or fail on swap/nonswap entries, failing follow_phys() and triggering a WARN_ON_ONCE() in untrack_pfn() and track_pfn_copy(), not properly calling free_pfn_range().

In free_pfn_range(), we either wouldn't call memtype_free() or would call it with the wrong range, possibly leaking memory.

To fix that, let's update follow_phys() to refuse returning anon folios, and fallback to using the stored PFN inside vma->vm_pgoff for COW mappings if we run into that.

We will now properly handle untrack_pfn() with COW mappings, where we don't need the cachemode. We'll have to fail fork()->track_pfn_copy() if the first page was replaced by an anon folio, though: we'd have to store the cachemode in the VMA to make this work, likely growing the VMA size.

For now, lets keep it simple and let track_pfn_copy() just fail in that case: it would have failed in the past with swap/nonswap entries already, and it would have done the wrong thing with anon folios.

Simple reproducer to trigger the WARN_ON_ONCE() in untrack_pfn():

<--- C reproducer ---> #include <stdio.h> #include <sys/mman.h> #include <unistd.h> #include <liburing.h>

int main(void) { struct io_uring_params p = {}; int ring_fd; size_t size; char *map;

     ring_fd = io_uring_setup(1, &amp;p);
     if (ring_fd &lt; 0) {
             perror(&quot;io_uring_setup&quot;);
             return 1;
     }
     size = p.sq_off.array + p.sq_entries * sizeof(unsigned);

     /* Map the submission queue ring MAP_PRIVATE */
     map = mmap(0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE,
                ring_fd, IORING_OFF_SQ_RING);
     if (map == MAP_FAILED) {
             perror(&quot;mmap&quot;);
             return 1;
     }

     /* We have at least one page. Let&#039;s COW it. */
     *map = 0;
     pause();
     return 0;

} <--- C reproducer --->

On a system with 16 GiB RAM and swap configured:

./iouring &

memhog 16G

killall iouring

[ 301.552930] ------------[ cut here ]------------ [ 301.553285] WARNING: CPU: 7 PID: 1402 at arch/x86/mm/pat/memtype.c:1060 untrack_pfn+0xf4/0x100 [ 301.553989] Modules linked in: binfmt_misc nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_g [ 301.558232] CPU: 7 PID: 1402 Comm: iouring Not tainted 6.7.5-100.fc38.x86_64 #1 [ 301.558772] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebu4 [ 301.559569] RIP: 0010:untrack_pfn+0xf4/0x100 [ 301.559893] Code: 75 c4 eb cf 48 8b 43 10 8b a8 e8 00 00 00 3b 6b 28 74 b8 48 8b 7b 30 e8 ea 1a f7 000 [ 301.561189] RSP: 0018:ffffba2c0377fab8 EFLAGS: 00010282 [ 301.561590] RAX: 00000000ffffffea RBX: ffff9208c8ce9cc0 RCX: 000000010455e047 [ 301.562105] RDX: 07fffffff0eb1e0a RSI: 0000000000000000 RDI: ffff9208c391d200 [ 301.562628] RBP: 0000000000000000 R08: ffffba2c0377fab8 R09: 0000000000000000 [ 301.563145] R10: ffff9208d2292d50 R11: 0000000000000002 R12: 00007fea890e0000 [ 301.563669] R13: 0000000000000000 R14: ffffba2c0377fc08 R15: 0000000000000000 [ 301.564186] FS: 0000000000000000(0000) GS:ffff920c2fbc0000(0000) knlGS:0000000000000000 [ 301.564773] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 301.565197] CR2: 00007fea88ee8a20 CR3: 00000001033a8000 CR4: 0000000000750ef0 [ 301.565725] PKRU: 55555554 [ 301.565944] Call Trace: [ 301.566148] <TASK> [ 301.566325] ? untrack_pfn+0xf4/0x100 [ 301.566618] ? __warn+0x81/0x130 [ 301.566876] ? untrack_pfn+0xf4/0x100 [ 3 ---truncated---

Published: May 19, 2024
Updated: Dec 24, 2025
CVE: CVE-2024-35877
Severity: Medium
Exploit:
CISA KEV:

CVSS v3:

Severity: Medium
Score: 5.5
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CWEs:

CWE-401

Affected Software
References

Software	From	Fixed in
linux / linux_kernel	2.6.29	4.19.312
linux / linux_kernel	4.20	5.4.274
linux / linux_kernel	5.5	5.10.215
linux / linux_kernel	5.11	5.15.155
linux / linux_kernel	5.16	6.1.85
linux / linux_kernel	6.2	6.6.26
linux / linux_kernel	6.7	6.8.5
linux / linux_kernel	6.9-rc1	6.9-rc1.x
linux / linux_kernel	6.9-rc2	6.9-rc2.x
debian / debian_linux	10.0	10.0.x

Deep Security Visibility Without the Complexity

SynScan provides clear, real-time security insights so you can monitor your attack surface, spot risks early, and act fast—without extra complexity.

No setup fees
5-min deployment
Cancel anytime

Book a Demo

Frequently Asked Questions

What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.