CVE-2025-39735: Linux kernel · jfs: fix slab-out-of-bounds read in ea_get()
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.1 High · fixed in 5.4.0-1147.157~18.04.1 : patch Linux kernel soon.
Data as of 26 Oct 2026, 16:39 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 22% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.4.0-1147.157~18.04.1, 5.4.0-1152.159~18.04.1, 5.4.0-1150.159~18.04.1 +85
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 18 Apr 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Patches and advisories
- ubuntu.com/security/notices/USN-7585-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7585-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7591-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7591-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7591-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7592-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7593-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7594-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7591-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-7597-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7597-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7598-1 (opens in a new tab)
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azure-nvidiapkg:deb/ubuntu/linux-azure-nvidia?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
In the Linux kernel, the following vulnerability has been resolved: jfs: fix slab-out-of-bounds read in ea_get() During the "size_check" label in ea_get(), the code checks if the extended attribute list (xattr) size matches ea_size. If not, it logs "ea_get: invalid extended attribute" and calls print_hex_dump(). Here, EALIST_SIZE(ea_buf->xattr) returns 4110417968, which exceeds INT_MAX (2,147,483,647). Then ea_size is clamped: int size = clamp_t(int, ea_size, 0, EALIST_SIZE(ea_buf->xattr)); Although clamp_t aims to bound ea_size between 0 and 4110417968, the upper limit is treated as an int, causing an overflow above 2^31 - 1. This leads "size" to wrap around and become negative (-184549328). The "size" is then passed to print_hex_dump() (called "len" in print_hex_dump()), it is passed as type size_t (an unsigned type), this is then stored inside a variable called "int remaining", which is then assigned to "int linelen" which is then passed to hex_dump_to_buffer(). In print_hex_dump() the for loop, iterates through 0 to len-1, where len is 18446744073525002176, calling hex_dump_to_buffer() on each iteration: for (i = 0; i < len; i += rowsize) { linelen = min(remaining, rowsize); remaining -= rowsize; hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize, linebuf, sizeof(linebuf), ascii); ... } The expected stopping condition (i < len) is effectively broken since len is corrupted and very large. This eventually leads to the "ptr+i" being passed to hex_dump_to_buffer() to get closer to the end of the actual bounds of "ptr", eventually an out of bounds access is done in hex_dump_to_buffer() in the following for loop: for (j = 0; j < len; j++) { if (linebuflen < lx + 2) goto overflow2; ch = ptr[j]; ... } To fix this we should validate "EALIST_SIZE(ea_buf->xattr)" before it is utilised.
References
- ubuntu.com/security/CVE-2025-39735 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-39735 (opens in a new tab)
- git.kernel.org/linus/fdf480da5837c23b146c4743c18de97202fcab37 (opens in a new tab)
- git.kernel.org/stable/c/0beddc2a3f9b9cf7d8887973041e36c2d0fa3652 (opens in a new tab)
- git.kernel.org/stable/c/16d3d36436492aa248b2d8045e75585ebcc2f34d (opens in a new tab)
- git.kernel.org/stable/c/3d6fd5b9c6acbc005e53d0211c7381f566babec1 (opens in a new tab)
- git.kernel.org/stable/c/46e2c031aa59ea65128991cbca474bd5c0c2ecdb (opens in a new tab)
- git.kernel.org/stable/c/50afcee7011155933d8d5e8832f52eeee018cfd3 (opens in a new tab)
- git.kernel.org/stable/c/5263822558a8a7c0d0248d5679c2dcf4d5cda61f (opens in a new tab)
- git.kernel.org/stable/c/78c9cbde8880ec02d864c166bcb4fe989ce1d95f (opens in a new tab)
- git.kernel.org/stable/c/a8c31808925b11393a6601f534bb63bac5366bab (opens in a new tab)
- git.kernel.org/stable/c/fdf480da5837c23b146c4743c18de97202fcab37 (opens in a new tab)
- ubuntu.com/security/notices/USN-7585-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7585-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7591-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7591-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7591-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7592-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7593-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7594-1 (opens in a new tab)