Linux: Use of Uninitialized Variable
CVE-2024-26882 is a high-severity use of uninitialized variable vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions ec6bb01e02cbd47781dd90775b631a1dc4bd9d2b, 77fd5294ea09b21f6772ac954a121b87323cec80, 5c03387021cfa3336b97e0dcba38029917a8af2a as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.69% chance of exploitation within 30 days, higher than 54% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to ec6bb01e02cbd47781dd90775b631a1dc4bd9d2b or 77fd5294ea09b21f6772ac954a121b87323cec80 or 5c03387021cfa3336b97e0dcba38029917a8af2a or 60044ab84836359534bd7153b92e9c1584140e4a, whichever matches your release line, or a later version.
- Update SIMATIC S7-1500 TM MFP - GNU/Linux subsystem to V1.1.1 or a later version.
- Update Linux Kernel to 5.4.273 or 5.10.214 or 5.15.153 or 6.1.83, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | c54419321455631079c7d6e60bc732dd0c5914c5 up to, but not including, ec6bb01e02cbd47781dd90775b631a1dc4bd9d2b; c54419321455631079c7d6e60bc732dd0c5914c5 up to, but not including, 77fd5294ea09b21f6772ac954a121b87323cec80; c54419321455631079c7d6e60bc732dd0c5914c5 up to, but not including, 5c03387021cfa3336b97e0dcba38029917a8af2a; c54419321455631079c7d6e60bc732dd0c5914c5 up to, but not including, 60044ab84836359534bd7153b92e9c1584140e4a; c54419321455631079c7d6e60bc732dd0c5914c5 up to, but not including, c4c857723b37c20651300b3de4ff25059848b4b0; c54419321455631079c7d6e60bc732dd0c5914c5 up to, but not including, f6723d8dbfdc10c784a56748f86a9a3cd410dbd5; c54419321455631079c7d6e60bc732dd0c5914c5 up to, but not including, ca914f1cdee8a85799942c9b0ce5015bbd6844e1; c54419321455631079c7d6e60bc732dd0c5914c5 up to, but not including, b0ec2abf98267f14d032102551581c833b0659d3; and 1 more ranges | ec6bb01e02cbd47781dd90775b631a1dc4bd9d2b, 77fd5294ea09b21f6772ac954a121b87323cec80, 5c03387021cfa3336b97e0dcba38029917a8af2a, 60044ab84836359534bd7153b92e9c1584140e4a, c4c857723b37c20651300b3de4ff25059848b4b0, f6723d8dbfdc10c784a56748f86a9a3cd410dbd5 |
| Siemens | SIMATIC S7-1500 TM MFP - GNU/Linux subsystem | before V1.1.1 | V1.1.1 |
| Linux | Linux Kernel | 3.10 up to, but not including, 5.4.273; 5.5 up to, but not including, 5.10.214; 5.11 up to, but not including, 5.15.153; 5.16 up to, but not including, 6.1.83; 6.2 up to, but not including, 6.6.23; 6.7 up to, but not including, 6.7.11; 6.8 up to, but not including, 6.8.2 | 5.4.273, 5.10.214, 5.15.153, 6.1.83, 6.6.23, 6.7.11 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.3 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: net: ip_tunnel: make sure to pull inner header in ip_tunnel_rcv() Apply the same fix than ones found in : 8d975c15c0cd ("ip6_tunnel: make sure to pull inner header in __ip6_tnl_rcv()") 1ca1ba465e55 ("geneve: make sure to pull inner header in geneve_rx()") We have to save skb->network_header in a temporary variable in order to be able to recompute the network_header pointer after a pskb_inet_may_pull() call. pskb_inet_may_pull() makes sure the needed headers are in skb->head. syzbot reported: BUG: KMSAN: uninit-value in __INET_ECN_decapsulate include/net/inet_ecn.h:253 [inline] BUG: KMSAN: uninit-value in INET_ECN_decapsulate include/net/inet_ecn.h:275 [inline] BUG: KMSAN: uninit-value in IP_ECN_decapsulate include/net/inet_ecn.h:302 [inline] BUG: KMSAN: uninit-value in ip_tunnel_rcv+0xed9/0x2ed0 net/ipv4/ip_tunnel.c:409 __INET_ECN_decapsulate include/net/inet_ecn.h:253 [inline] INET_ECN_decapsulate include/net/inet_ecn.h:275 [inline] IP_ECN_decapsulate include/net/inet_ecn.h:302 [inline] ip_tunnel_rcv+0xed9/0x2ed0 net/ipv4/ip_tunnel.c:409 __ipgre_rcv+0x9bc/0xbc0 net/ipv4/ip_gre.c:389 ipgre_rcv net/ipv4/ip_gre.c:411 [inline] gre_rcv+0x423/0x19f0 net/ipv4/ip_gre.c:447 gre_rcv+0x2a4/0x390 net/ipv4/gre_demux.c:163 ip_protocol_deliver_rcu+0x264/0x1300 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x2b8/0x440 net/ipv4/ip_input.c:233 NF_HOOK include/linux/netfilter.h:314 [inline] ip_local_deliver+0x21f/0x490 net/ipv4/ip_input.c:254 dst_input include/net/dst.h:461 [inline] ip_rcv_finish net/ipv4/ip_input.c:449 [inline] NF_HOOK include/linux/netfilter.h:314 [inline] ip_rcv+0x46f/0x760 net/ipv4/ip_input.c:569 __netif_receive_skb_one_core net/core/dev.c:5534 [inline] __netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5648 netif_receive_skb_internal net/core/dev.c:5734 [inline] netif_receive_skb+0x58/0x660 net/core/dev.c:5793 tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1556 tun_get_user+0x53b9/0x66e0 drivers/net/tun.c:2009 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2055 call_write_iter include/linux/fs.h:2087 [inline] new_sync_write fs/read_write.c:497 [inline] vfs_write+0xb6b/0x1520 fs/read_write.c:590 ksys_write+0x20f/0x4c0 fs/read_write.c:643 __do_sys_write fs/read_write.c:655 [inline] __se_sys_write fs/read_write.c:652 [inline] __x64_sys_write+0x93/0xd0 fs/read_write.c:652 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b Uninit was created at: __alloc_pages+0x9a6/0xe00 mm/page_alloc.c:4590 alloc_pages_mpol+0x62b/0x9d0 mm/mempolicy.c:2133 alloc_pages+0x1be/0x1e0 mm/mempolicy.c:2204 skb_page_frag_refill+0x2bf/0x7c0 net/core/sock.c:2909 tun_build_skb drivers/net/tun.c:1686 [inline] tun_get_user+0xe0a/0x66e0 drivers/net/tun.c:1826 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2055 call_write_iter include/linux/fs.h:2087 [inline] new_sync_write fs/read_write.c:497 [inline] vfs_write+0xb6b/0x1520 fs/read_write.c:590 ksys_write+0x20f/0x4c0 fs/read_write.c:643 __do_sys_write fs/read_write.c:655 [inline] __se_sys_write fs/read_write.c:652 [inline] __x64_sys_write+0x93/0xd0 fs/read_write.c:652 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use of Uninitialized Variable
The code uses a variable that has not been initialized, leading to unpredictable or unintended results.
How developers prevent this class of flaw
- Ensure that critical variables are initialized before first use.
- Most compilers will complain about the use of uninitialized variables if warnings are turned on.
- When using a language that does not require explicit declaration of variables, run or compile the software in a mode that reports undeclared or unknown variables. This may indicate the presence of a typographic error in the variable's name.
More Use of Uninitialized Variable vulnerabilities (CWE-457)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/5c03387021cfa3336b97e0dcba38029917a8af2a
- git.kernel.org/stable/c/60044ab84836359534bd7153b92e9c1584140e4a
- git.kernel.org/stable/c/77fd5294ea09b21f6772ac954a121b87323cec80
- git.kernel.org/stable/c/b0ec2abf98267f14d032102551581c833b0659d3
- git.kernel.org/stable/c/c4c857723b37c20651300b3de4ff25059848b4b0
- git.kernel.org/stable/c/ca914f1cdee8a85799942c9b0ce5015bbd6844e1
- git.kernel.org/stable/c/ec6bb01e02cbd47781dd90775b631a1dc4bd9d2b
- git.kernel.org/stable/c/f6723d8dbfdc10c784a56748f86a9a3cd410dbd5
Other references
Recent Use of Uninitialized Variable vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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