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Linux KernelOperating system · Linux

CVE-2025-37749

HIGH · 7.1 CVSS v3.1 Published 2025-05-01
Fix available
A fix is available. Upgrade to 5.4.293 / 5.10.237 or later.
See remediation →
73/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: net: ppp: Add bound checking for skb data on ppp_sync_txmung Ensure we have enough data in linear buffer from skb before accessing initial bytes. This prevents potential out-of-bounds accesses when processing short packets. When ppp_sync_txmung receives an incoming package with an empty payload: (remote) gef➤ p *(struct pppoe_hdr *) (skb->head + skb->network_header) $18 = { type = 0x1, ver = 0x1, code = 0x0, sid = 0x2, length = 0x0, tag = 0xffff8880371cdb96 } from the skb struct (trimmed) tail = 0x16, end = 0x140, head = 0xffff88803346f400 "4", data = 0xffff88803346f416 ":\377", truesize = 0x380, len = 0x0, data_len = 0x0, mac_len = 0xe, hdr_len = 0x0, it is not safe to access data[2]. [[email protected]: fixed subj typo]

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-125

The code reads past the end (or before the start) of a buffer, returning memory that was never meant to be exposed. Attackers use it to leak secrets like keys or to defeat memory-protection defences. Remediation is validating indices and lengths before every read.

General guidance for the out-of-bounds read class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 2.6.13, < 5.4.293>= 5.5, < 5.10.237>= 5.11, < 5.15.181>= 5.16, < 6.1.135>= 6.2, < 6.6.88>= 6.7, < 6.12.24>= 6.13, < 6.13.12>= 6.14, < 6.14.3= 2.6.12= 6.15
Debian LinuxOperating system
Affected:= 11.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.4.293 / 5.10.237 / 5.15.181 or later
Fixed in 5.4.2935.10.2375.15.181
Vendor patch git.kernel.org →
Recommended fix High confidence

Linux Kernel 6.1.135+ or 6.12.x (latest stable) | Debian 11: Apply vendor security updates

  1. Identify the current kernel version using `uname -r` or `cat /proc/version`
  2. For production systems: upgrade to a kernel version >= 6.1.135 (LTS) or >= 6.12.x (latest stable)
  3. On Debian 11 systems: apply vendor security updates via `apt update && apt upgrade linux-image-*` to receive the patched kernel
  4. Verify the fix is applied by checking that the ppp_sync_txmung function includes bound checking for skb data length before accessing data[2]
  5. After kernel update, reboot the system to load the fixed kernel
  6. Alternatively, if immediate kernel upgrade is not feasible, apply the specific commit 1f6eb9fa87a781d5370c0de7794ae242f1a95ee5 to the kernel source and rebuild
Caveat Kernel upgrades may require driver/rebuild for proprietary kernel modules; ensure compatibility with system hardware before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $3,200. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-37749 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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